Since a friend of ours is officiating the wedding, I am writing up the entire ceremony on my own with the help of google

Unfortunately, I haven't really been able to find much on including the children from a previous marriage into the ceremony. I found where you say vows to each other, but I think they are too shy for that and they would be too uncomfortable which would make it really awkward.
Ideally, I would like to just add something onto the end of my vows to FI and then work a way of presenting them both with their own rings or necklace. I just can't figure out the wording.
We will both be saying the same vows to eachother, but I am going to add this to the end of mine:
"I not only stand here and promise to be a loving and faithful Wife, I promise to be a patient, loving and caring Mother to Ava and Isla. I accept them as my own and promise to always be there for them, to listen to them, advise them, and love them until the end of our days."
Should I say something about presenting them with the ring/necklace or should I have the officiant say something and ask them to come up so that I can give it to them? At what point should I do it - after I am done saying that part in the vows or when FI and I present our rings to eachother?
ETA: I'm also going to post this in Ceremony Ideas.