Divorcee Pete Conway, 64, who is getting married to a woman of the same age as the Take That star, wants his 38-year-old son to perform at the celebrations when he weds Melanie Mills, reported Sun online.
"Robbie is so, so pleased for me. Melanie and I have been together for over two years so we thought we'd get engaged.
"The next thing is to plan the marriage. When it happens Robbie might sing, wouldn't that be lovely. We've got to all get together and plan it. I will see Rob next week and we'll have a little celebration," he said.
Conway, who got divorced when Williams was three, is now expecting their first child with Mills.