The link finally worked for me. They will ship one bag for free but it appears to be UPS/Fed ex. 3-5 day lead time. cant make that work for a saturday flight.

I will use the twlight service to check the night before because I have four kids and it is easier. I'm then going to use the https://united.maketraveleasier.com/ to have them delivered from the destination aiprot to the house...they seem to say they will deliver in less than four hours. but nothing free there. with several checked bags, the fees seem reasonable.