Introduction and question

Hi im mama coop and just started raising chicks incubating for the first time and out of 12 eggs 2 hatched however our power went out for 6 hours so had to transfer them to gmas house so im thinking the humidity dropped and shrink wrapped most of them so we did go buy 3 silkies. And currently incubating 9 was15 but out of 7 frizzle d'uccle only one was fertile and out of 8 leghorns all were fertile. So hopefully that one d,uccle hatches. So since the new ones will be weeks younger than our other chicks is it wise to brood them apart? And introduce them slowly to one another