Can I restrict visitation rights due to CAS involvement ?

In order to restrict or govern potential exposure of a child to a third party, it is necessary to obtain a court order, or agreement. You would need to determine what provisions in a court order or agreement would specifically ensure that your daughter does not have contact with this third party. But, in addition, the other issue is to ensure that those provisions are enforceable. This is a relevant issue, as when a party applies for custody and/or access, that party must file an Affidavit in Support of Custody and Access and the party must indicate who they will be living with. You would need to tender the evidence as to the third party's children being involved with the CAS. The next step should be to gather whatever evidence you have in relation to the involvement of the CAS and further details as to how that third party may prejudice the best interests of your daughter.