Linked claims from legacy to UC?

I have a client who is married, with 2 kids and not working

He gets tax credits

He was on JSA, but was (wrongly) advised to close his claim and claim ESA

His doctor refuses to give him a sick note. He needs to be back on JSA

He is struggling to get JSA, as he is now in a full roll out area, and they are saying he must claim UC

He gets Tax credits, and he only closed his JSA claim last week, so im wondering if he can link the new JSA claim with the one closed last week

JC+ told me there are no linking rules for people in a full UC roll out area

The fact he still gets tax credits should mean he can clain legacy perhaps?

Any thoughts would be welcome

I fear that as you’re in an full UC area he can not put a new claim in for any legacy benefit anymore - all he can do is claim UC and the tax credits will stop and support for children will be paid by UC.

Though if anyone has different experiences in a full UC area please say…