"use to join" is correct and usable in written English.
You can use it when referring to two or more things being united together. For example, "We used glue to join the two pieces of wood."
Armand the psychic often used to join us.
South Korean workers used to join a company expecting lifetime employment.
"I used to join in – it was something anyone could do".
Southern children used to join either the rebels or government-backed militias.
Youth in the village used to join the local young men's association on this day.
The conceit ends up as a distraction, an unnecessary, weak glue used to join its two powerful parts.
As a student at Stuyvesant High School in New York, Ms. Akbar said that to establish a spiritual routine, she used to join two close Christian friends in a Christian prayer group.
It is this broader view that the Neuberger exhibition favors: anything in which heat was used to join metal parts qualifies.
"My best memories are of fishing," Walker said, "I used to join my brothers, fishing in matches for the local pub team, the Raven pub.
