Struggling with names

My two kids have long strong names my daughter is Addison Maria Bulhoes Joy and my son is Lincoln Thomas Wellington Joy.  I know middle names I would use for both boy or girl but am having a hard time making them ring together and then adding a first name to them as well...  Requirements for first name ending in on.  Boys middle names I would like to use are Francis and Clyde and girls middle names are Florence and Margeret.  Accepting suggestions!