Joint claims for the vulnerable

I’ve a 21 y/o care leaver who has a partner aged over 30 who claims ESA for the both of them. He has his WCA coming up and expects to be kicked off benefit imminently.

Can my young lady claim ESA as lead claimant?—she says she’s been told she can’t.

She has been invited to a work focused interview next week—she has conditions which would allow her to claim ESA—is there any scope to reduce conditionality as she is also not fit for work?

Are there any APA arrangements like UC on ESA?—my client’s partner has drug addiction and I am concerned about the ESA money being paid directly to him.