If you lived in your own home which you owned outright or with a mortgage, the correct financial decision would be to sell your investment property as it would allow you to clear your other loans and contribute to a pension.
However, that is not the situation here.
Your father does not want you to sell your investment, and if you do sell it, there is a chance that you would be disinherited. So there really is no debate on it, you need to hold onto your investment. And as it happens, it's not a very bad investment.
Furthermore, you prefer your investment property as a home to live in and will move back when your father dies. So I don't really know why we are even discussing the potential sale. It's just not on the table for discussion.
Forget about pension contributions for the moment. Forget about your children's education for the moment. Focus on paying down your expensive debt if you can. When your father dies, sell his home, clear your debts and mortgage and you will be in a solid financial position.