Children of the bride and/or groom are often a part of second marriages. If either of you has children, invite them to participate in the ceremony.

Teens make nice junior ushers and junior bridesmaids. Very young daughters can, of course, be flower girls, and little boys, ring bearers or pages. Conversely, if the ceremony is to be small or the ages of the children would make them unsuitable for these roles, you might simply ask them to accompany you down the isle, or meet you at the altar.

Children do not always welcome the opportunity to participate in wedding ceremonies. If you children seem unwilling to play a role in the ceremony, you should respect their feelings.
Incidentally, if you share custody with your ex-husband, let him know about plans to include your children in the ceremony.