Singleton hauled in 39 receptions for 622 yards and six TDs as a junior.
"North Texas and San Diego State have offered Austin," Mann continued. "Coach Lewis from San Diego State is recruiting him. Louisiana Tech is close to offering Austin and might offer both during the summer.
"Things are starting to pick up for all of them. Tulane seems like a great fit for the twins. I've been hoping they'd get interest there. UL (Ragin' Cajuns) and Old Dominion appear to be next to offer the twins."
Austin plays running back at Crosby, while Aston - still waiting on offer No. 1 - is a prep quarterback that Mann compares to Russell Shepard due to his versatility.
Aston will likely move to receiver in college.