I'm going to start off with saying I don't own leos. I have lots of crested geckos and dragons so I can only give you an idea here
I generally just put the two females in question in together. IMO an introduction isn't really nessecary, but I also can't see it being a bad thing, assuming they don't instanly fight. You want to make sure the two girls are close to the same size so neither gets bullied. 44g and 58g is pushing it for size difference in my opinion but grams don't tell the whole story. If the girls look to be abut the same size-ish (sorry...that's vague. maybe post a picture of the two, lol) they should be alright. You'll need at least one extra hide, it's good to have several, and possibly another food dish. You'll need to watch out for signs of weight loss or biting.
As for the male, when you get him you will need to put him in a seperate tank to quarantine before introduction, I'm sure you already knew that though. Persoanlly I would also keep the extra tank just in case you ever need to seperate one for whatever reason. Also, IMO I wouldn't keep the trio together year round, I would seperate the male when not breeding so he doesn't bug the ladies, or injure himself from too much breeding. Hope that helps.