When planning for a wedding where one or both of the couple have divorced parents, you're going to have to take a few precautions into account when organising the big day. It helps if the parents in question still get on, but if they don't, it's best to rely on conventional etiquette as much as possible to avoid causing any offence and to keep the day running smoothly and without any big arguments.
Convention dictates that on a wedding invite, it's the bride's parents who are listed, since they're the ones giving the bride away. In the case of divorced parents, these names appear at the top, only with the father's name on the line below the bride's mother's, as described by the Crane & Co website. If the mother has remarried, she's titled "Mrs." with the new husband's name afterward, while if she hasn't remarried, she's titled "Mrs." with her first, maiden and married names following this.
New Partner Problems
It's possible that in some extreme cases, the potential presence of a mother's or father's new partner might be enough to cause the other parent to announce that he or she isn't coming to the wedding. In this case, common sense dictates that a good first step is simply to try to talk through the issues with the involved parties. As the Frugal Bride website suggests, as a last resort, the wedding couple can simply not invite the new partner in question if such an invite is going to cause serious problems on the day.
While it's not proper to indicate who's paying for a wedding via the invites to the service, as noted by the Crane & Co website, if there's a need to point out who's footing the bill, this can be done via the reception invites. These secondary invites are also a good place to mention stepfathers and stepmothers, by convention omitted from the service invites.
During the service, you can seat both divorced parents close to the front, but have the father sitting in the second row, behind the mother who's in the front row, as suggested by the Frugal Bride website. Alternatively you might organise other guests as a "buffer zone" between them, if such seating isn't possible.
When it comes to the dining tables at the reception, you'll need to consider who sits where. As the typical wedding reception features one long high table that seats the wedding party, as noted by the County Bride website, you should look to organise the seating so that neither divorced parent is seated too close to each other, yet both are reasonably close to their child, whether that's the bride or groom. If one parent has remarried, or both have, the conventional seating plan will have the new partner seated at the same end of the table as their spouse, though not necessarily next to them.