I’m very very sorry for you loses. I know the pain, and it really hurts, because my wife and I lost our child last January due to a miscarriage.
There is no doubt your little ones are in heaven. Life begins at conception, so it is very right and fitting to give them names even if they did not make it to full term. We chose a neutral name to begin with on the day of the miscarriage, Francis. Then as my wife was sitting on our couch sobbing and crying out to God that she just wanted to know if it was a boy or girl, something incredible happened later that day, a miracle. Yes, a lamp we had bought for our babies nursery was unplugged, as I had just finished putting the shade on it and stepped back to look at it, it lit up bright pink, not once, but twice, and we both saw it. We went from sorrowful to instant joy. We knew then by the grace of God the child we lost was a baby girl, then we gave her a complete name, Katie Francis.
There is not a day that goes by that she is not a part of our lives, There have been many other miracles since then. You see, God is the God of the living, and He does but build walls between those were love, no matter the age, but rather He builds bridges with His infinite love.
So as a father who feels your pain, please please please give your two children a name and never forget them, not even for a day as they will always be with you interceding for you and your family so that one day they will be reunited with their mom and dad. While losing our child was the greatest pain I’ve ever felt, just having her in our life is the greatest joy we have ever known. God along with our Blessed Mother know the pain of losing a child, but they also know the flip side to that pain, the joy of eternal life. Your children know that joy too!!!
May God bless and comfort you.