ILR received, what happens to current dependants?

I successfully received my ILR (long residence) yesterday at Croydon PEO, and I now have a question regarding my dependents, who are currently dependents to my Tier 2 General visa which was due to expire in 2018, which is technically not valid since getting my ILR yesterday.

Is there any time limit when they must apply for FLR(M) or can they remain in the UK as Tier 2 dependents for some time? No one seem to have the answer - even immigration officer at Croydon PEO couldn't answer this question yesterday.

There is no timeframe within which they must apply on FLR(M) but sooner is better than later as FLR(M) will reset their clock to zero for ILR.

They should also not travel on their current visa as they risk being refused re-entry to the UK.