Transfer Portfolio into an ISA?

I currently have a Managed Monthly Income Portfolio on InvestEngine but it isn’t in an ISA - I started it last year when I was already tied into one from another provider.

I haven’t paid into an ISA this tax year, and would like to move what I currently have in my InvestEngine Portfolio into an ISA with yourselves, and then continue to add to it going forward.

How would I go about this in the easiest way?

Im not an i fa but presume there is no exit charges ? Tried to move from vangard once but a bit of hassle

Most other platforms ask you to sell and buy again after cash transfer.
Isa to isa transfers of holdings are standard though.
Not sure of Investengine, expect to be same