If you are worried about your child being introduced to new people, speak to the centre as soon as possible. They will not allow this without the consent of all parties, but it is important that they understand your concerns and consider these when making plans about what might be in the best interests of your children.
Initially, it is best if these sessions are used for the other parent and children to strengthen relationships in this very unfamiliar environment.
In terms of the needs of your child, it is worth remembering that a lot has changed in their lives recently, and maybe changes are still happening. This is likely to be very unsettling and hard to get used too, even if your child seems to be managing well. What children need is consistency and security. Therefore, it is usually best not to introduce them to new people that might make them feel insecure until other elements of their lives feel a little more stable for them.
However, it might be possible for other people to attend child contact sessions with you after you have been using the service for some time. This will need to be discussed with the centre, prior to making any arrangements. You should not come to the centre with visitors without letting them know. Typically, they will want to seek the agreement of all parties before approving such requests.
If it is agreed, then the child can be introduced to new people, or people that they have not seen for a very long time. A supervised centre or social worker will be able to assist with planning this (re)introduction to ensure that this happens in the best way for the child. For most children, it is important that nothing is sudden or unplanned.