Best approach for fighting a 2 v 1?

My last game was a 3 v 3 Arabia. I was Mongolians on the right flank, Bulgarians on the left. We had a Spanish pocket player in the center, but the issue was they seemed really new. They pretty much worked on eco the whole game and were still behind me and the Bulgarian player. Whatever, everyone was new at some point and you can't always expect to get carried by your pocket player.

That being said, the Bulgarian player seemed to be a notch better than their opponent. They both went for Cav and the Bulgarian player was winning. I'm convinced that if I could have just held against the player on my flank and the pocket player long enough for my ally to win their fight we could have won the game. Our pocket player was behind but I'm certain they would have eventually fielded an army, and if I could boom under pressure from two players I could have won.

I did the usual tricks (house walls, defensive tower, spears on woodline, counter attack with my remaining scouts, palisade walls driving raids under TC fire, and eventually mangonels and defensive castle) and was able to reach castle age under pressure, but I just couldn't boom while defending.

What was the best call? Build a TC in the corner and boom from there? Go full feudal military and throw everything into an offensive push to try and knock one of them out?