Unity Candle

Background My parents are divorced, civil but barely. FH mom is deseased and his dad is remarried.

Most of the weddings I have went to the mom's light the unity candle. Do you think it is ok to have my mom and FH father light it? I ask because my mom thought it was the parents together who light it. and I don't want to offend FH step mom but they are clsoe but not that close.