The chick doesn’t need siblings if she has a mum. The only reason you would have to get her some siblings is if she was hatched by an incubator. Of course you can also just get some more chicks if you want, I snuck two chicks under by mother hen when she was sleeping one night. It is risky to sneak chicks under a mother hen in case she sees them as an “imposter“ and kills them. I don’t know what the best way to give your hen chicks is, as much as this worked for me it is risky (my hen is also a silkie so that could’ve made the risk lower). It is your choice what you do. Best of luck hatching