Hi,
I can't really think of anything negative.I have 3,1male and 2female a month after.My male was almost 4mths when I got the girls.They just adjusted well together.When we only had 1 he would whine cry when we left him at home,I think he was lonely.But now he has someone to play with so he doesn't mind if we're not there.I think its great,if I'm busy he has the girls to keep him occupied.They get along better than I thought.
You can tell your hubby that Esme's is lonely when you leave her home and another one will keep her company and she won't be lonely.Also tell him that if she has a playmate than you have more time to pay attention to him
Hope that helps,let us know if you can convince him.....