Hiya

i hav been lookin at these pics and other pics of the same hamsters on another forum, and i think we have now come to the conclusion that they are both males, but i agree that it is still very early to be able to sex them correctly.
I advised Toria to put the males in with the dad at three weeks old as i have always done this with no problems. I think this is the perfect age (if they have been correctly sexed) for them to be placed with the dad, as at this age any adult robos will still treat these very much as babies and will not see them as a threat - so there will be no danger to the babies or the adults. Hopefully this will also give them a good start to stay together in the future, but of course they will need to be monitored closely, especially as the babies reach 3 or 4 months old.
As Nella has said, you will be safe from unwanted pregnancies at least till they are 5 weeks old, and i usually find that another couple of weeks after that is usually fine too - but of course you do want to get them sexed by 5 weeks old if you can

If you are certain of the sexes, and are happy to remove them from the mother now, then i am sure they will be fine with dad now, but just monitor them carefully

Good Luck - just let me know if you need any further info.
Tammy x