A notice of their application had been posted in the dairy's window and published in local newspapers.
SWDC said there had been no objections to their application.
Mrs Patel said there would only be three places to buy alcohol in the town just as there was when Chungs Supermarket was open.
"There was Chungs Supermarket, we are filling the gap, it's not like there is an extra liquor store. To survive you have to make a change, it's hard to survive as a dairy, supermarkets are killing small businesses."
The Bottle-O Featherston liquor store and Featherston Four Square are the other two off-licences that sell alcohol.
The Featherston community's Facebook page shows residents are not keen on another store.
People felt shocked to see the dairy turn into a bottle store, said Emma McCleary, a resident and administrator of the Facebook page.
"The general feeling is that we have already got a stand-alone bottle shop, a supermarket and two pubs in a community that has issues with violence, alcohol and young people roaming around. We don't really need another bottle store."
Ms McCleary said while technically the dairy owners were replacing Chungs, it was the fact there would be an increase in alcohol availability that concerned people.
Peter Jackson, newly elected Featherston community board member, said he felt divided on the issue.
"On the one hand, I'm not in favour of an additional liquor outlet in Featherston, but there is only one other liquor store."
If it provides a bit of competition, it was good for responsible alcohol consumers, he said.
Mr Jackson said there was a potential the liquor store would impact negatively on the community.
"That's something that the police and the community board will keep a very close eye on."
He said it was a matter of the board, social organisations and police actively monitoring and responding to any consequences.