Do your kids suffer from some sort of mental or emotional disability that prevents them from remembering people w/out a tangible object to associate with that person? Or that my child is perhaps playing his XBox and thinking "I love my StepDad because he bought me this XBox, and it helps me remember him", as opposed to "Man, I love playing Skylanders!"?
And yes, sometimes my kids and stepkids complain about what I've given away or whatever. But it's not actually my job to care whether or not the kids are happy every second of every day. It's my job to keep peace in my household, as much as is possible with 7 kids. Sometimes, that means getting rid of things that cause conflict.