Oh, brother.

The Knicks retained J.R. Smith’s brother, Chris Smith, on their 15-man roster, releasing rehabbing injured 6-foot-10 forward prospect Jeremy Tyler in a surprise move. However, coach Mike Woodson and Tyler’s agent said he still could re-sign with the Knicks after he gets healthy.

On Wednesday, Woodson said “respect” for J.R. Smith would be a factor in weighing whether to keep Chris Smith, who played just 20 minutes during the preseason and shot 1-of-7.

Chris Smith was asked Friday, before the Knicks preseason finale, an 85-83 loss to Charlotte at the reopened Garden, if he’s annoyed at the perception he was kept around because he’s J.R.’s brother.

“It bothers me a lot because I think people don’t really look at my talent, they just look at J.R. is here and he’s been here,” Chris Smith said. “I think if we weren’t brothers, there would be no recognition of me being his brother.

“Has it helped me? Of course. That’s my big brother. People look for us to be together all the time. People look for us together. So he has helped me a lot. He’s helped me offensively, and I feel like I’m pretty good on defense because I’ve had to guard him growing up.

“I feel like I earned my position on the team and I’m going to keep on earning my way here.”

One agent told The Post this week if the Knicks kept Smith, the NBA should look into the situation as the maneuver could be against the spirit of the collective bargaining agreement.

NBA spokesman Tim Frank said, “It wouldn’t be appropriate to comment on speculation.’’

When Chris Smith hired his brother’s agent, CAA’s Leon Rose, in the spring and fired Marc Cornstein, The Post reported the brothers’ free agency was seen in some league circles as “a package deal.”

Meanwhile, Tyler had foot surgery in early September, and is not expected back until late November — at the earliest. For two straight days, Woodson said the Knicks would not kick Tyler “to the curb,’’ and he may not have been lying despite the player’s release Friday.

Woodson said the club is “keeping an eye’’ on Tyler, whose rights are owned by the D-League’s Santa Cruz franchise. Woodson said Tyler could be “four, five weeks away, maybe longer’’ from playing.

“We told him we’d like for him to go to the D-League and keep tabs on him,’’ Woodson said. “We’re still interested in him down the road, based on how he plays.’’

Tyler’s agent, John Baker, said he hopes his client can rehab his foot at the Knicks’ facilities. But first the Knicks’ D-League affiliate in Erie, Pa., would have to work out a deal with Santa Cruz, according to a source.

That way, Tyler can play rehab games in Erie instead of Santa Cruz and then sign. At that point, the Knicks could choose to cut center Cole Aldrich instead of Chris Smith.

Aldrich, a former lottery pick, survived the cut despite an up-and-down preseason, as did combo guard Toure’ Murry, who had a brilliant preseason.

In addition to Tyler, the Knicks cut forwards Ike Diogu and Josh Powell, disappointing undrafted rookie C.J. Leslie and former Nets swingman Chris Douglas-Roberts.

Woodson said Aldrich was kept over the impressive Diogu because he was younger and more of a center than the Nigerian.

Chris Smith, a DNP in the last two preseason games, said fans on Twitter “have been coming at me’’ and feels they “overlook’’ his having played on Louisville’s Final Four team.

Woodson wouldn’t address the brother factor Friday, saying only that Chris Smith is “a young player that needs D-League seasoning.

“The bottom line is he’s on our team,’’ Woodson added. “We made a commitment to him. When you make a commitment to a young player, you got to develop him.’’

After Chris Smith tore his patellar tendon during last training camp, the Knicks cut him but rehabbed him the entire season.

“He hasn’t had enough reps for us to realize if he’s going to be a player,’’ Woodson said. ‘We don’t know yet. If he doesn’t pan out, things happen.’’

Smith is expected to spend much of the season getting playing time in Erie. Smith has an unique clause in his pact that his contract becomes fully guaranteed on opening night. Most minimum deals don’t get guaranteed until the Jan. 5 deadline. Hence, the Knicks could cut Smith in December when Tyler is healthy and he still would get all his money.

“It’s a great opportunity for myself,’’ Smith said. “[The brother talk] just fuels more hunger to my fire.’’