Force sale of a property (ex gf)

[Kiwi70]

My ex GF and I owned 2 x properties. She now lives in Property 1 (4 bedroom) with our young daughter & new BF and the other property (3 bedroom) is rented to her parents. We did a deed of seperation and I gave up all financial interest in both properties but my name is still on the mortgages. She is supposed to be using 'best endevours' to release me from the mortgages but no joy yet. What can I do... can I force her to move into the smaller property and sell the larger one? I cant get a decent mortgage as the other properties that I am imdemnified against are been factored in.