I am a 'coffee morning type'.
Largely because when DD started school in Sept, I knew no-one, and I didn't want that to be the case.
So I smiled at everyone, said hello/good morning and talked (only a bit, and not great with that kind of thing)to the people who were on their own.
I also took DD to all the parties in the 1st term, and talked to people there-people are in less of a rush, so even the working parents have time to chat.
1st party, I chatted to one mum. 2nd party, I chatted to 2 together. Then one day the next week, I asked the mum from the 1st party if she fancied a 'playdate' on a Wednesday, and she did.
We've now started meeting regularly for coffee on a Thurs, have had playdates etc, and I have a new group of friends as does DD.
If you want to make friends with these women-is that what you want?-you are going to have to make the first move. You say you aren't there enough to know who belongs to who, but it goes both ways. Their DCs may be dying to have your DD round to play, but their parents may not know who her mum is.
And to be honest, if I'm going to invite someone and their child to my home for 2+ hours , I'd like to have at least said 'hello, how's it going, have you started the 'Taj Mahal out of Marshmallows' project yet?' to them, so I can know whether we will get on reasonably well or not.
Does that make sense?