There's a ReVi guideline in the main 5th ed rulebook:
"Sustain or suppress a spell cast by another with level less than half the (level + 5 magnitudes) of the Vim spell."
So can you use this to sustain a broken circle ward, if cast when the circle is being broken? I find it stylishly appropriate, at least. Then afterwards fix the circle, and cast a ring duration "sustain" ?
Idle speculation... could come in handy sometime.