What am I?

[Diakonia]

A priest need not be bi-ritual to concelebrate, only to be the sole or principal celebrant of a ceremony in the liturgical service of a Church sui iuris other than his own. He may concelebrate in any Church sui iuris provided that he adhere to the requirements of the Code:

Canon 701 CCEO

A concelebration between bishops and presbyters of different Churches sui iuris for a just cause, especially that of fostering charity, and for the sake of manifesting unity between the Churches, can be done with the permission of the eparchial bishop, while observing all the prescriptions of the liturgical books of the principal celebrant, having removed any liturgical syncretism and wearing the appropriate vestments and insignia of his own Church sui iuris.

 

[Aelred_Minor]

I have been to MANY Byzantine weddings held in Roman Churches. Any Catholic priest of any Rite can “concelebrate” at a wedding. I have been to RC weddings where Orthodox priests took part as well. It would be VERY RUDE to put a priest in a pew with the rest of the congregation.

I assume that by “Orthodox priests took part as well” you don’t mean they concelebrated. That would be a no-no.