David Rigby, good point, but that can be handled by deferring the split-up/spin-off until the dust settles. They can operate the plan as a multiple employer plan until then. Yes, lot's of reasons to dislike multiple employer plans, but this is a case where doing so for 5 minutes (figuratively speaking) may make sense.
On the other hand, what are we talking about here? Are there 5, 6, 10 employees, or 100+? If this is a tiny plan with very modest assets I might turn 180 and suggest terminating it.