When Andy Rivers was hired by MInneapolis TV station WJM to be their sportscaster in the mid 1970's, he soon became a casual boyfriend to the associate producer of the newscast, Mary Richards.
It never came up in the show, and it probably wouldn't have mattered to the open-minded Mayr, but it's pozz'ble, just pozz'ble, that Andy Rivers had been previously married. And if so, perhaps he had a son, one that was even named after him.
It could be that Andy Rivers, Jr. grew up not wanting to share the same name as his father - not so much that he resented Andy Rivers for breaking up the family but because he wanted to follow his father into the broadcast news biz. So maybe he amended his name slightly and became known as Sandy Rivers. We've seen Sandy Rivers as Robin Scherbatsky's co-anchor on a local New York City news station, but now she's working for him as his news researcher at another station.
'The Mary Tyler Moore Show'
'How I Met Your Mother'