I'm trying to optimize some future travel plans and one of the ideal options would be to have an adult get an award ticket and 2 kids be added with paid tickets (TK gives a significant discount to kids on cash tickets, but awards cost the same).

I can't simply make the kids' reservation separately and choose adjacent seats, since they're too young for the TK booking system to accept the reservation without at least 1 adult.

How can I work around that? Is it possible to first book the adult award reservation and then, perhaps via the call center / sales office, to book the kids in some way that connects/references the adult PNR?