Lateral thinking tells me that if a donk drops off, it won't go without allowing a lot of fuel to go in the same direction.
I suppose it depends on the precise nature of the separation and the location of the ENG FSOV's.
Whereupon I imagine the most important consideration is the position of the XFEED valve.
From personal experience it is a highly uncomfortable sensation when one realises, inspite of both donks turning, a significant fuel imbalance exists.
