IMS that situation would break the parma connection. I prefer the mentioned hub & spoke method described by Fruny, and limit the extent of parma to Voice range more than visibility. Visibility has all kinds of problems given what magi can do.
Xavi
It is not a big deal, and I am sure Falls would gladly just retract his Parma if it was a sticking point for players involved.
But the wording seems pretty clear and absolute...
Xavi's hub model is all nice and well, but it is not what the rules say. I really don't like adding non-existant restrictions.
I am famous for missing that one specific word that totally changes the meaning of things though. Anyone else able to shed any light? I am not looking for house rules or what restrictions/benefits you may add. What is the absolute RAW meaning?
Well, I always wondered what happens during a figth. This may be THE setting you want your grogs be protected.
Both party can see each other? Well that is quite impossible in a fight, as you have turn left and rigth to avoid being hit. By the way both paties see one onother means they face each other, so if they want to move in a direction either both have to walk sideways ore one backwards. I cannot image how this will add to flavour.
One party is able to see the other? Well, at least this works when you can see the back of your shieldgrog. But be aware not to sudenly turn around! or blik with your eye... This does not sound very funny either.
I believe the rule was introduced to avoid a magus to grant the grogs protection and send them out while staying behind. So I think the "voice range" option suggested by Xavi is the best solution though not RAW.
Or even something along the lines of the old 4th edition range of "Near".
I'd be inclined to be lenient on the interpretation. Yes, a magus may blink or turn their head. Voice or Near are fair ways to describe it, but I think I would allow a magus to protect his grogs while standing on the top of his tower. How he got there without breaking the protection is another issue (for what it's worth, my players are only now discovering that hiding behind a shield grog would b a wise thing to do... It took one player's magus to be incapacitated in both campaigns he plays in to realize that... So we haven't yet reached the point where they think about protecting their grogs with a parma)
How similar players are! In our saga it also took two incapacitated mages to stop the heroic stride into battle headlong. Only the Flambeau is kind of subburn but than again he is of the school of Ramius combined with Apromor and has a fair chance surviving if prepared.
Heheh. In our case it was a dead magus (and a scramble for the exit door) what caused that reaction 
Long time ago, in 3rd edition, but the result was the same.
I know it is not RAW at all. The RAW sounds rather... unthought (would that be a word?) here: if you live in a mountain and have some sight range spells to see farther away you can send your grogs 20 leagues away and they still will have parma? Yeah, right....
Xavi
Indeed, that occured to me as well reading over this discussion. In Im of a decent level and you can 'see' your grog anywhere. This, while obviously rather gamist, is within the spectrum of the rule... though I would say outside of the intent.
I believe what you are looking for is ' ill-considered '.
It would be more helpful if Parma were defined as a magical art/ability of it's own with more fully developed write-ups on how it works... both range and sharing-wise, and perhaps some additional discussion of theory and other use options. ( Like tokens or circle casting etc. )
For myself I think it should not be sight reliant. More akin to a spreading the 'bubble' of the shield out over a wider area. I'm not certain how picking specific people by touching them, and then letting them wander all over creation, 'works' with the theory/fluff of how parma functions, being a mystical 'shield' spell. Or at least with my understanding of it.
Btw, marko, the text you have quoted at the top of the second page of the thread reads "can see the other", not "the others" thus indicating that the case under consideration is that either the magus has to be able to see the grog or the other way round. If other grogs are also protected, it their relation to the magus that counts, not one protected grog to another.
Hub and spoke 
Okay, I am comparing 4th and 5th editions, and the wording I keep quoting seems quite deliberate. The rules are totally different in each.
ArM4, p.55 & p.73; ArM5 p.66 & p.85
Begin the Protection
ArM4: Only those designated during the ritual are protected, and a whole new ritual is needed to cover someone new.
ArM5: You must touch each person to begin the protection, and they must be consenting.
Strength of Coverage
ArM4: Subtract 3 from Parma score, and you need a minimum score of 4 to protect anyone. Everyone gets the form bonus.
ArM5: Reduce Parma score by three, to a minimum coverage of Magic Resistance 0. Only the magus received the Form bonus, though a magus protected by the Parma of another still receives their own Form Bonus.
And here is the important one…
Duration and Range of Protection
ArM4: Range of protection is only fifteen paces, though they can step in and out of range without breaking the spell. Protection lasts until the next sunrise or sunset, though you may cancel the effect at will.
ArM5: Protection “lasts as long as at least one character can see the otherâ€. You can cancel protection at will from any distance.
These are specific deliberate changes, and intentional new wording. No legacy text here. The rule for protecting others with your Parma has been changed in these three specific ways.
I like 4th's edition better, then.
Cheers,
Xavi
Well, you have inspired me with an idea though. Way back in 2nd edition Parma was a spell. My idea is having a Mastery Score for your Parma. The score would add as a bonus to your resistance (not multipled), and add to the number of people you could protect. Then, like spell mastery, each level gives you one Mastery Ability. One such ability could be Xavi's circle Parma. Another one could be Extending Range, first to merely being able to sense one another, then to Arcane Connection if taken twice. The Parma Folds from True Lineages could be other examples of Mastery Abilities for Parma.
I would add something like "within theoretical sight", ie if it suddenly goes dark, do they loose protection? Is the range lower in darkness? If someone is just barely around a corner?
If someone sits or lies down just enough to get out of sight?
I would say as long as they are within a certain unhindered/unblocked/open range(from protector(probably determined by parma ability score, and possibly boostable by reducing protection level)), protection retained.
I prefer 4th edition myself as well for the parma rules and for ranges.
I've been discussing with my own home campaign troupe about the possibility of converting our 4th edition game to 5th edition. However, there are just some things that we feel 5th edition doesn't really do well to truly make it worthwhile. Ranges is one of those things. After some discussion we came up with the possible house rule that the different ranges would be:
Per -> Touch/Eye -> Near -> Voice/Sight -> Arcane Connection
I think that the "near" rule is more appropriate for the Parma because we can all easily point out examples of how one can abuse or create a contrived situation where Sight as a range is absurd.
Hmm... the biggest "oversight" here would be target structure and ring. Room can be overcome with Near and Voice ranges easily.
Ring and structure have no equivalents in your list. Are you refusing to use those? Just cvurious; Ring/circle spells are one of the most used ones IMS 
Xavi
Ring and structure are targets(as you say yourself), he stated ranges...
May be parama-range should be classified by "As long as one party can sense the other." This way it is in RAW that you can only affect things you can sense. Excluding arcane connections you can extedn your parma to all those situation you want it to work: Being in complete darkness but in the same room (you can hear the other person breathing), on a battlefield (you hear him), when you are in the same room but looking into different directions (again hearing)
restricting the range to hearing would not be good as parma would stop the moment you become deaf (same problem as turning off the lights).
But if you are blind and deaf you need to touch the person for th eentire time. I find this O.K.