Is there a tradition of who your two witnesses are?
We have our booklets from the registrar and we have to choose and let them know when we have our meeting to discuss words, vows, readings etc. My first thought was to ask my step-mum and step-dad, as step-parents don't get traditional roles in a wedding (we still have all our real parents with us to do the traditional things). However, then both witnesses are from my family which might cause some raised eyebrows from PILs.