Cockatiel babies & baby sitting adults

I have 3 cockatiels - 2 Males and 1 Female (my other female passed away suddenly) they are in the one aviary together and all seem to get along well. I have only acquired one of the males recently, the other pair have been together for a few years. I recently put in a breeding box as the female started laying eggs in the food containers (before I got the second female or male), They laid one clutch of 5 eggs in the box, sat on them day and night and nothing happened (back in around May perhaps, so it was beginning of winter which i though was strange), The female laid another clutch 3 weeks ago (4 eggs), the mum and dad sat on them again vigilantly, and now I have 2 babies, one hatched late Wednesday & the other on Thursday night, it's now saturday and no more have hatched. The parents are feeding them and taking turns in the box, my only concern, and i can't seem to find anything on this, is that the second male cockatiel is ALSO taking turns looking after the babies and sitting on the eggs. Is this a bit weird? The mum and dad are outside the box preening each other and so forth, while the ring-in step daddy is keeping bubs warm!

The mother is a pearl pied (grey/yellow) with orange cheeks (but who came from a lutino and whiteface pair) and father is a pied grey/yellow with orange cheeks (unsure of parentage). The babies so far are one yellow fluffy and one white fluffy - which i read means it will be a whiteface adult. Can this be the mothers parentage coming through in her babies colours, or is there a possibility that she "did the dirty" with the step-daddy as well - he is a whiteface?
<< Mother
<< babies

<< step-dad on the nest

<< dad

Soooo... Cute! Sorry- I don't know anything though.