Some suggestions

Use segments of the video material for children: Children in Prayer - Children's Version, downloadable from the GDOP site, or available locally from Tony Copple. NB: beware - the downloads sometimes come in unfamiliar languages, so don't leave this till the last moment!

Map of the world, on the ground, for the children to pray over (doubles as a geography lesson)

Crafts, banners, crowns  Provide materials so they can create or embellish these items. They can all be brought with them as they rejoin the adult group for the finale

A picture of Jesus that the children can bring as they rejoin the adults  This helps reinforce them as special and unique.

Rejoining the adults. Towards the end of the GDOP service, the children should parade back to the main location to the applause of their parents and other adults as they come bearing banners, crafts and wearing crowns. This has always been a special moment. If appropriate one of more of the children may be ready to lead a prepared prayer before the assembled company, prior to the the children rejoining their parents. This part of the service is a great photo op!

GDOP committee member for prayer, Lois Schriel, jschriel(at)sympatico.ca, has previously fashioned children's ministry for GDOP, and can be contacted for advice and ideas. Lois' #1 suggestion is that once you have taken responsibility for this ministry, and you pray for guidance, God will give you more ideas than you will have time for!