Marriage celebration, for an eastern Catholic, is not valid without the witness of a priest, except for the unusual circumstance of no priest available for a month. There are several additional impediments: spiritual relationship (CCEO 811), abduction of either spouse (CCEO 806), affinity with brothers or sisters of the former spouse (CCEO 809), and public propriety (CCEO 810).
Also for anointing of the sick:CCEO 737.2. In the Churches in which it is the custom that the sacrament of anointing of the sick be administered by several priests, it should be seen to inasmuch as it is possible that this custom is preserved.
CCEO Canon 739
- All priests, and only priests, validly administer the anointing of the sick.
- The administration of the anointing of the sick belongs to the pastor, parochial vicar and to all other priests for those persons committed to their care in virtue of their office; any priest can licitly administer this sacrament with at least the presumed permission of these mentioned, indeed, in case of necessity he must do so.