ORCHARD PARK, N.Y. (AP) Rex Ryan isn't the only member of the Ryan family working with the Buffalo Bills this week.

Rob Ryan, Rex Ryan's twin brother, has been spending time at Bills practices as Buffalo prepares for Sunday's game against Philadelphia. Rob Ryan was fired as defensive coordinator of the New Orleans Saints in mid-November and was spotted leaving the practice field with the team on Wednesday and Thursday dressed in full Bills attire.

''I think he contributes by being here,'' Rex Ryan said. ''I think the guys love the fact he's here. There is a lot of respect for him. It's good to get him out there. ... I know Rob's had a great time being around it. Obviously, he misses being around this type of atmosphere. He's been impressed with this team, I can tell you that much.''

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Rob Ryan was let go by the Saints on Nov. 16. The Saints have struggled all season on defense and are last in the NFL in yards and points allowed. Ryan has also served as defensive coordinator with the Dallas Cowboys (2011-12), Cleveland Browns (2009-10) and Oakland Raiders (2004-08) after four seasons as linebackers coach with the New England Patriots (2000-03).

Rex Ryan reiterated there are no immediate plans for his twin to join his staff, which he has maintained ever since his brother was fired by the Saints. Rex Ryan said his brother's trip will end Saturday morning and that he will not travel with the team to Philadelphia.

But Rex has not ruled out the possibility of coaching together sometime in the future.

''I'll stick with the chalk line, you never say never,'' Rex Ryan said. ''It is fun to be around him, there's no question about it, and I know he's a great coach. But I think we purposely have tried to set different courses. But I never rule out that possibility. Obviously he's a great coach and if that happens, that'd be great.''

The Bills promoted linebacker A.J. Tarpley from the practice squad to the active roster.

An undrafted free agent out of Stanford, Tarpley spent the first 12 weeks of the season on Buffalo's active roster before being released on Nov. 30. He returned as a member of Buffalo's practice squad on Dec. 1.

In 11 games, Tarpley has two tackles and one sack.

To make room for Tarpley, the Bills placed linebacker Tony Steward (back) on injured reserve.

Safety Aaron Williams was cleared to practice and made his return to the field Thursday. Williams has been on injured reserve since Oct. 14 due to a neck injury. Earlier in the week, Rex Ryan said Williams had around a 50-50 chance of returning to play in games before the end of the season.

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