Deed of trust

[Chrisinthemorning]

When DH and I bought our first house together he was a FTB. I had sold my previous house and had £100k equity.
We have a deed of trust that states that if we divorced, the first £100k equity is mine and the rest is split 50/50.
I have £45k that i want to lump into our joint mortgage to bring the balance down.
Can I update the deed of trust to state £145k me and then split?
Thank you

Your deed of trust isn't binding, as you are married. Necessarily.

Nor would a variation.

We were married when we had it done- does that make a difference?

You would have to make a post-nuptial agreement - essentially saying what would happen were you to divorce.