We have a chair that straps to the dining chair, I think it's fischer price, that has three tilting positions. One is back for an infant (for a bottle) then a middle position (I started my son in this position when he was eating solids), and then the full upright position. It also transitions to a booster to push up to the table.
I know the reccomendation isn't to give solids before 6 months, but my dr. "allowed" us to start Ethan at about 4 months rice cereal as he was drinking massive amounts of milk and never seemed satisfied. However, I agree that if your LO is unable to sit up it's dangerous.