Jesus himself changed the meaning of the Seder meal. He took the unleavened bread, broke it, and said "This is My body, which is for you; do this in remembrance of Me." He took the Passover cup, and said "This cup is the new covenant in My blood; do this, as often as you drink it, in remembrance of Me."
So, if Christ show Christina the meaning behind the meal in regards to the New Covenant, I don't think that it is an issue for Christians to celebrate the Seder in this fashion.
Christina = Christian. Sorry, I need another cup of coffee, and the spell check did not catch this. :-O