Money in Trust for Minors

[Guest]

Nil rate band Discretionary Trust in Will of surviving spouse which is going to be appointed out. Two daughters of deceased are Executors/Trustees and are inheriting the estate but want money invested for 3 grandchildren of deceased who are minors. We can leave the money in the NRBDT and appoint out the balance but I need to advise the daughters the consequences of doing this. I know about tax returns, charges etc but what will the Trustees need to do when the children reach 18? Also, can you appoint out of the NRBDT to a bare trust as I think this type of trust in this circumstance would be more suitable?