[Help] Need to introduce dogs to kids

Last July my boyfriend moved me and my two large dogs (Not 100% sure, but believe Weimaraner/Curr mix-2 years, and a Mastiff/Hound mix-11 months) into his house. They've adjusted to the house wonderfully, but they're both protective of me and their house.

My boyfriend has three children (9, 10, 12) that the dogs have not met yet, but will be meeting at the end of the month when they come to visit for a week. The children have rooms here and the dogs are allowed in the kids rooms. We have things in there we need to get to everyday and the dogs follow us. I think they should be familiar with the children's scents and will recognize them as members of the house.

We are trying to figure out the best way to introduce the family. The dogs will be at daycare while we go up to get the children, and we'll pick the dogs up from daycare the morning after we get home. We have some good resources to use, but aren't quite sure the best route to take. We have a fenced yard to create a boundary that can be used, and there is a very nice off-leash park a few blocks up the road.

Suggestions/recommendations/experiences are welcome. Thank you in advance for the help!