Can I put these chicks together?

[peep peep]

I have 2 silkie chicks and one showgirl that are all 1 1/2 weeks old. Tomorrow, I'm getting 2 more silkies, but these are 2 weeks old and from a different breeder. Can I put these chicks in the same brooder as my 1 1/2 week year olds?

 

[Judy]

Usually it is considered OK to mix ages if they are all under 4 weeks. Watch for topknot picking with those breeds, though.