It�s a difficult situation and I have the greatest sympathy for you. I have friends who are in similar circumstances. They have two children and have given up asking their mother/mother in law to care for them.
But when I speak with her, she has a different position. She is upset with how her son and his wife live their lives. She�s distraught because her grandchild is brought to her without nappies, is dirty, hungry and appearing in generally poor health. She�s also upset because they never contact her or include her in anything, except for when they want her to babysit. From her body language and words, it is clear that her feelings are hurt and she feels used.
By no means am I suggesting any of this is in regards to you. Relationships are always complex, especially in light of your additional circumstances.
With limited knowledge of the dynamics here: might you be able to find someone else to care for your child for the few hours you are out? And then, during the ensuing weeks, find time to have some visits with your in-law, not requesting anything, but merely to be with one another as friends. You may find that her demeanour begins to change, especially if she has felt that she was being used.
I�m not going to throw out the �church� thing. But I will offer that within my own parish, we have a large number of senior citizens who provide sitting services so young people can get out and do shopping, apply for jobs and even have a break from time to time. In other words, they become an extended family.
It�s just food for thought.
I wish you every success
Fr Bill