2 baby showers update

So a couple of days ago I posted about how my SOs mom wanted to throw another baby shower separate from the baby shower my mom wanted to plan and how I wasn't happy about it. Well my SO talked to her and told her that we both only want one big baby shower where all the family can meet and get to know each other before the baby comes. She basically told him she was going to have a separate baby shower for her own family regardless of what we want. Her first excuse was the place that we were talking about having it at was to small but now she talking about having a baby shower at her house, which is in the same city that we planned on having it, and inviting me and my family. I'm confused how are you going to throw a baby shower for a baby that isn't yours and inviting his mom who is inside of her? She then tells him that she was going to keep his stuff at her house. So basically you aren't going to give his parents his gifts for their kid? It just pisses me off and I know this is not going to turn out well in the future. Makes me not want to even let her keep him often because I feel like she is going to overstep the boundaries that need to be set between parents and grandparents.