Porting a mortgage with a Lifetime ISA?

Hello,
First post so thanks in advance for your help.

My partner and I are looking to buy together and I'm currently researching the best way to approach things. I have a lifetime isa (as a first time buyer), and he owns the home we live in now. He remortgaged approx 6 months ago to a much better rate. The mortgage he has is portable and we would obviously like to avoid paying early repayment fees if possible when we buy a place together and take out a mortgage together. We would be looking to borrow more than what he currently owes on the current house. So my questions are...

-Is it possible to add another person (i.e. me!) to the mortgage if he can port the mortgage to the new property?
-If so, could I use my lifetime isa funds as a deposit as part of this process?
-Lastly, would my partner also be able to use some of his savings to pay down as a deposit as part of this process (reducing the amount we would need to borrow in the mortgage?)

I read somewhere that the porting application process is similar to that when applying for a new mortgage, which made me think this might be a possible option, and that by doing this we could possibly use the lifetime ISA (& bonus) whilst avoiding any early repayment charges.

Any advice or info you might have is appreciated

Thanks!