Many of them are in the FAQ for the site...

http://steptalk.org/faq#a2

It's in the F.A.Q. section on the left if you need it later and can't find this. I'm sometimes lost without it.

•sm = stepmother
•sd = stepdad
•bm = biological mother
•bf = usually biological father but every now and then some use for boyfriend
•sd = step daughter
•ss = step son
•bs = biological son
•bd = biological daughter
•dw = darling wife
•dh = darling husband
•dd = darling daughter
•ds = darling son
•poa = power of attorney
•cs = child support
•mil = mother-in-law
•fil = father-in-law
•pas = Parental Alienation Syndrome

F.A.Q. has a list of these.

DH is Dear Husband
SO - Significant Other
FSD - Future SD
SF - Step Father

My other blog uses one that we don't use and should.

DGI - Don't Get It.