ISA allowance

Hi, I have recently opened a FT account & I am using it alongside a previously held Halifax share trading account. I held two isas in cash with a building society but have recently transferred the cash in this years isa (20/21) to the Halifax leaving my isa for last year (19/20) where it is. Can I move the cash in last years isa to a FT isa & still use the funds to transfer existing held shares into it. Hope I’ve explained myself, this question has been bugging me for a while.
Thanks for any replies…Del