My question OP is that you stated she never reciprocated.
Do you mean that she never helped anyone in your group or do you know that she has never helped someone else?
I think the who Idea that is being proposed about D being selfish (because that is essentially what is being said) really grates on me unless the OP knows all the details of D's actions inside and outside of the group. Does she take holiday and birthday gifts but never reciprocates or is it JUST this issue with the baby clothes that bothers you. If it is just the baby clothes and she's always been find with other "gifts" or "gift giving occasions" (did she bring gift to the baby shower?), I find it presumptuous to assume that you know her financial situation and her own decisions regarding giving and helping other.
Who says I'm assuming? I gave her two gifts, one for baby, one for her. She never even thanked me. I gave her a birthday gift, same story. She got people to babysit for free all the time. I'm not saying she should have payed me, but she never, ever even suggested it. I only got calls whenever she needed something. In hindsight, I was not the only one.
Willynilly, that's exactly how I feel, I just couldn't explain it right

The group passed on second hand clothes and toys to her as well, and she sold them all. It made everybody go 'eh?'.
I mean, if I give my second hand clothes to friend X, and we have a friend C in the group trying for kids, I would be very, very upset if friend X went and sold all the second hand clothes. And yes, I didn't explicitly say 'please don't sell these but pass them on', but honestly, isn't that sort of implied?
Just to clarify, I don't mind people selling new clothes or new gifts they got. What feels wrong is to sell second hand clothes you got for free through the grapevine. In my opinion, the intent behind that gift is to pay it forward. To ignore that feels, to me, entitled.