This storyline is such a mess that I am really not sure how to answer you!
The fact she 'doesn't need the money' because she is in a coma is neither here nor there - she isn't dead, she could recover (unlikely, but possible). We don't know their previous financial circumstances but the one thing Reiss has always been clear about is that the money is Debbie's, not shared.
You'd think she'd be getting CHC but she apparently isn't because Sonia told Bianca last week that Reiss is 'still paying for her care home' - how could he afford that for years on end?
Reiss says he has LPA - how? Debbie would have had to sign the LPA forms, and she's in a coma. Even if you are married, you still need LPA for your spouse if they are incapacitated and you need to act on their behalf.
We don't know if the writers have made mistakes, or if Reiss is lying through his teeth, but the way the storyline is going probably the latter.
@Viewer23 from what I remember, Reiss said he cannot have children naturally and Sonia suddenly decided she had to have a baby, which is why they went the IVF route. I don't know if we ever got further 'details'.