Likely only seating hiccup is schedule change or a/c change, where your companions may get bumped out of C+ and require a call to get them back. Only time I've had an issue with moving a companion to C+ is where I've already been upgraded and am no longer in C+ myself, which doesn't seem like it would be an issue here.

One potential problem is if those 5 award seats were based on you being a PM. If you're no longer traveling with them on same reservation, you may not be able to secure 4 seats at that mileage level assuming no status for them. Hopefully calling and getting all of this done simultaneously would help eliminate that if an issue.

DL will also extend companion baggage rights to your companions so long as you all check-in together, so you don't lose that benefit either. (Based on my experience of splitting award tickets so my upgrade will clear to give to Mrs. Phil2016 when traveling together as a family.)