well before my ornate found a way out of my tank he was about 10" and he was in with a small 3 inch palmas polli.... never ate it but they use to best buddies. it is kinda funny the biggest in the tank and the smallest.
At their current size I doubt there will be any issues. I have a fair mix and there has been infrequent aggression, in fact they seem to enjoy hanging to together.
My Lap gives the ornate a bite once in a while, but does not pursue of harass it, and the ornate pretty much ignores everything smaller. In fact there is a 5" dojo loach in with them (supposed to be a snack) that was added at 2" and now thinks its a bichir.
The ornate will eventually double the size of the senegal, so I would expect it will be at the adult sizes that you may run into issues. A large tank may mitigate the risk though.
That said, I plan to keep my 2 senegals with the big boys.....