What happens with the crusade is decided after the outcome of econ's battle.
I think I intend to have them assault the force besieging Damascus in a night attack however. I could send them Elberhard with a few mailed knights as reinforcement, but he wouldn't be able to join the crusade as there are not enough units left in Aleppo to do so unless I were to split off troops from Leopold's army which I don't intend to do (not good roleplaying to split the troops just to create a new crusading army of one man)

If they win the battle, I'll be using the two nearby spies to open the gates so they can take Damascus this year still.