Mixed age couple query

Pension age claimant in receipt of state pension, pension credit with severe disability addition (savings and guarantee), higher rate AA, HB and CTR, is about to move in with working age claimant on UC with LCWRA, no PIP.

If they move in together, she has to be added to his UC claim, so massive income drop. If he reports himself as her carer, she could have LCWRA element at the end of the relevant period as she receives AA, and he could have carer element in respect of her. QBC says ‘where both claimants have LCW or LCWRA and one or both is a carer, the rules on awards of the elements are potentially ambiguous’. Is there likely to be an issue?

Many thanks