Some of the ones I have figured out are these, (at least I THINK this is what they mean!?)

DH = Darling Husband, Dear Husband, Dumb Husband, Dingbat Husband (you get the idea), when I write it, I mean Darling Husband.
DD = Daily Deal at M*QC [Missouri Star Quilt Company] or DD= Darling Daughter.
DS = Darling Son
SIL = Son in law or Sister in law
MIL= Mother in law or Monster in law [mine is sweet so no monster there]
DIL = Daughter in law
IMHO= In my humble opinion
BTW= by the way