M17 foster parenting

We have fostered a girl (7now)who we l8r were able to adopt. When her fully biological brother was born (1 now) we decided to keep them together and have to do it all again. So far nothing bad has happened , we r on the adoption track which is a long process, then last night the social worker texts us and says he needs fingerprinted ASAP and they'd have some1 pick him up. We don't know this person , as the usual worker is unavailable,  and our boy has never been away from us.  We went thru this with our girl and it was so stressful waiting for her to get home. In had hoped we wouldn't need to do this and we can't deny access or they can just take him . Very stressful time