Gift of equity with tracker mortgage?

Hi, I'll try to keep it short - Basically myself and my wife live in a two bed apartment on a tracker, just about out of negative equity. We are both classed as 2nd time buyers (She bought the property many years ago) Her mother is offering us her house (I say offer, we are buying it with a 2nd time buyer mortgage). We are meeting Ulster bank next week to enquire about moving the tracker to the new property for the outstanding amount on our current property plus a new loan for the balance. My question is this:

Can she gift us equity in the house so that we could use that instead of the 20% deposit?
Will that have any impact on the tracker moving over?
What would you consider to be the implications of doing the above if possible?

Many thanks
Jdq

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