Baby shower dilemma - should I invite his side??

I have a baby shower dilemma. It's going to be on Oct 22 in 3 weeks for my side, co-Ed with kids. My sis is throwing it at her house. I have a huge family and including my friends over 100 people are invited and currently about 40 are going. She has a decent size backyard, a heated pool, 2 sitting areas, a deck and a side grassy area about 20x40, plus the living room, dining room will be open. 
When we were first thinking about showers, My sis in law offered to throw one. So I opted out of a huge hall for everyone and just chose to do my sisters house for mine.  My husbands side has an invite list of 59 people (15 of those kids). I sent her the list back in the beginning of sept for a November shower. Since then we haven't heard anything and I doubt it's going on. First I told my husband to verify with his sister. But now he just wants to add on to mine and doesn't think it's fair that I have friends with plus ones who he doesn't know invited to mine and I can't even invite his family. He thinks only like 15 people from his side will go. Also his mom is older and in and out of medical appts and it doesn't look too good, so we want to include her as much as possible before it's too late. But the thing is, he also isn't on great terms with my sister and her husband who is hosting my shower. They haven't spoken in over a year and he made no effort to make an amends after we were done being separated 7 months ago. But he did that with my parents. Supposedly my dad gave him advice that he can't really talk to my sister about the past because of her strong personality etc but still. 
If my sis in law isn't throwing a separate shower, should I just invite his people out of courtesy and hope it's not too crowded? It's only 3 weeks away. I did put 1-4pm on evite saying to stop in whenever hoping it's going to be super casual.