Overbearing other grandmother

This is my first post.

My son and GF are expecting their first child (our first GC in January) this was a big shock as they had been through a really rocky patch around the time she must have just been pregnant. Her mother sent me a hurtful message about my son, I didn't respond. When they told us about the baby, they told her parents first, my son was suddenly a wonderful person again.

Her mother has become overbearing already and it seems she has been desperate to be a grandmother. She seems to be buying everything she can lay her hands on. We were informed that they were buying the pram, we were also informed that we could buy the cot. I would have liked them to use the beautiful cot we have lovingly kept since having our children but without even being seen the GF has rejected it, So we are to purchase a cot, having just discovered how much her parents have spent on the pram I am struggling to see how we can make an equal contribution.

I know it's not all about the money but I am slightly fearful about how things are going to pan out due to her mother being a bit overbearing and having way too much time on her hands.