Jamie,
I would agree that there was a moral obligation to take care of the orphans and widows of both sides. But the pensions were not the way the government could take care of that (from the perspectives of the time).
Anyone can join the SUVCW as an associate. We have several SUV/SCV dual members in our camp. However, only a certain percentage of camp members can be associates, the rest must be actual descendants of Union Veterans. We have several associates in our camp also.