Dear JW,
The Church does not forbid Catholics from having a Seder meal as a help in understanding our Jewish heritage. But such events must always be seen in the context of the fulfillment of the Old Law in Jesus and not used as a means of devotion.
First communicants are far too young to understand the subtleties of history and the relationship between Christianity and Judaism. The LAST thing they need is the addition of unnecessary elements that can be confusing when being introduced to the Eucharist. What is the pastor thinking of?!!
Fr. Vincent Serpa, O.P.