They believe they may be the first to have three family members elected to the same ward on any council in the West Midlands.
Councillor Milkinder, aged 61, a governance consultant, has represented the Heath Town area of Wolverhampton since 1991.
His wife, Jasbir, a 58-year-old management consultant, has been a councillor since 2012 and was re-elected this month.
Now their daughter-in-law, 33-year-old optician, Jaspreet, has been elected for the first time and will represent the same ward for the Labour Party.
She said: "It is really exciting having been elected and I am looking forward to working for the community.
"I had been vice-chairman of Heath Town Labour group and through this learned about what the councillors are doing and found it very interesting.
"I learned about the different people can make.
"I have always lived in Wolverhampton and want to do what I can for the local community."
Councillor Jasbir Jaspal said: "It is a very proud moment for us to have another family member elected and particularly a younger member.
"As a family we want to help our communities and we have always wanted to do what we can for everyone.
"We understand that we are probably one of the first families to have three members in the same ward on a council but have to do more research on this."
Councillor Milkinder, who is recovering from Covid-19 and having been in a coma for six weeks in New Cross Hospital, said: "It is a very proud moment for the family and I think she will do a good job for the ward.
"The ward selected her as a candidate as she does a lot for the local area."