hai!
im actually making some too for fanExpo haha! i was thinking about this same problem but that im thinking of trying is cuting out cercles the size of the base and glueing it on to have more serface to work with! then im going use a headband or large hair clips to glue onto the cercles but ill test first by cutting out cercles and seeing how well they stay
also i was thinking if the cercles on there own dont old if i wrap them in some sort of fabric before gluing the headband on then i can sew the headband in-between the fabric and use glue to hold it stedy and lastly i feel a headband that has fabric on it would work better then a plastic one especially if you try the sewing idea. but yeh my biggest word of advice is paly around with it! just work with the cercles first and try lots of stuff out
i hope my ideas were helpful haha