I do not understand this. Why would someone want to buy a house together with the mother, who has completely different financial conditions, and not mention his wife in the forum. The whole thing makes no sense. The mother should simply buy a little house for 2 units with her good income, then you can rent an apartment there at first. If the women still get along in 5 years, you can buy the apartment. I would never plan property with a parent if you already have your own family.