In most cases your family will not have seen your children for even longer than you and they too will have been very hurt by this experience and keen to see them again.
Seeing your child at a contact centre is a very emotionally provocative event for you and your child. Initially, it is best if these sessions are used for you and your child to build and strengthen your 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 (or too many people that they have not seen for a long time) 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 your 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.