My FH's parents are divorced, and have been since he was a child. They still get along "for the kids" but are two very different people and would never spend time together outside of events for their sons. Both of them are in long-term relationships but neither are married. FMIL has been dating her boyfriend off and on for the past few years. They break up like at least once a year - sometimes for months - but always get back together. FFIL has been with the same woman for 8 years; they are committed to one another but he's vowed to never remarry just out of principle.
My question is twofold ... first, do I / should I / can I have them walk down the aisle together? They're not a couple, so I don't know what the etiquette is really like for that. Second, if they don't walk together, should they walk with their current boyfriend/girlfriend ... or should we have someone else escort them or have them walk alone?
Any advice would be appreciated. Thanks!!