Well first, if this is following you around, it is you or someone in your family that is haunted, not the houses. Moving will not do you any good, as it will follow you to the next location. There are of course, times when features of the house or property may exacerbate the situation--as you said, you found some ritual paraphernalia which may have been used to open a portal--but sometimes there can be natural, geological features like nearby running water like a stream or river, or a high quartz content in the ground.
THAT being said, child spirits are often benign and pretty easy to get them to cross over since they did not have the time to form strong attachments to the physical realm. Often times they are scared, though, so some reassurance that someone they love will meet them can be key. You said you are a mother--and it's very possible that is the reason they are trying to get your attention. Because you understand children and they believe that you can help them. Treat them as you would your own, with kindness, compassion, and love.
In a quiet place, light a white candle and invite your spirit children to join you. Ask them if they would like to be crossed over to the other side. I'm not sure how much you can hear/feel them but a yes would be a lighter, higher vibrational feeling and a no might be a lower vibrational feeling (think flute vs. tuba). If it's a no, then they may just not answer at all. If you get the ok to cross them over, ask for help from your guides and the guides of the children. It's not important for you to have an already-open relationship with your guides--they are always with you and there to help you. They will pass on messages if you need them to. So ask them to call forward anyone that could help the children--be it a parent, grandparent, aunts/uncles, siblings, etc. Someone they would recognize and trust. Ask for these spirits to hold the hands of your child spirits as they cross over. You should be able to feel a change in the energy of your house immediately.
Hope this helps and if you have any questions, please feel free to ask.