I'm not sure how relevent this will be but I was really worried about age gaps especially thinking like if they are two or three years apart in school that's like a lifetime right? But now that we homeschool and are part of a homeschool co-op I realise and see how weird that was to think and the complete range of ages that play together and enjoy each other's company. It isn't really about school or not btw, just that that was an environment where I could really see it in action. And I mean you probably have friends of various ages right? I'm not worried at all now.

I found DD1 being almost 3 when DD2 came along was brilliant. She understood, she was independent in many things, there was no jealousy. I can't think of any cons actually. They play beautifully most of the time, by the time DD2 was proper playing age DD1 was an age where she understood how DD2 was still learning and might not understand ettiquette or rules properly (eg they play memory at 5 and 2 but DD1 is very understanding of DD2 turning over 3 at a time or things like that and helps her out patiently). She took role modeling for her sister very seriously so both are inspired by having each other really.