If a deacon is asked to officiate a wedding to a non-Catholic, there is a process, however the difficulties of mixed marriage must not be underestimated.
familyministries.org/www.inthespiritofcana.org/2.6.10.htmDifferences about faith and the very notion of marriage but also different religious mentalities, can become sources of tension in marriage, especially as regards the education of children. The temptation to religious indifference can then arise (
Catechism of the Catholic Church, #1634).
If possible, the Catholic minister should take steps to establish contacts with the minister of the other church or ecclesial community. In general, mutual consultation between Christian pastors for supporting such marriages can be a fruitful field of ecumenical collaboration.
Since for validity where one or both partners are Catholic, the marriage has to be contracted in the presence of the Ordinary, parish pastor, the priest, or deacon delegated by either of them (Canon 1108), the Catholic canonical form is to be observed also for mixed marriages (Canon 1127). However the Ordinary of the place for grave reasons, and without prejudice to the law of the Eastern Churches, can dispense the Catholic partner from the observance of the canonical form in individual cases. See
The Ecumenical Directory, 153, 154 (the reasons to justify such a dispensation are listed), and 155. If a dispensation from the canonical form has been given, it is still required for validity that there be some form of public celebration. (See Canon 1127, 2)
If a dispensation from the canonical form has been obtained and if invited to do so, a Catholic priest a Catholic priest or deacon may attend or participate in the celebration of a mixed marriage at another Christian church by offering prayers, reading from Scripture, or giving a brief exhortation. Alternately, if the Catholic priest or deacon will be presiding, he may, upon the request of the couple, invite the minister of the non-Catholic party to participate in the marriage ceremony. In any case there may be only one ceremony in which the presiding person receives the marriage vows.
Mixed marriages ordinarily follow
The Rite for Celebrating Marriage Outside Mass. The Eucharist is a symbol of unity, and celebrating a Christian marriage at Mass may make the celebration awkward for both parties by highlighting their differences in faith. If circumstances justify it and the non-Catholic party agrees to their having a Mass, The Rite for Celebrating Marriage within Mass may be used. However, it must be stressed that should there be a Mass, directives of
The Ecumenical Directory (159/160) and the Code of Canon Law (Canon 844) concerning reception of the Eucharist are to be observed. Couples should consult with their priest about this delicate matter
Note this: A deacon does not have faculties or powers of the state unless he celebrates weddings in the confines of a church by permission of the bishop. So a deacon cannot do a beach/garden etc wedding and neither can a priest in most dioceses without very special permission and exception. In the 10 years I have been a deacon, none has been granted in my diocese that I am aware of.
As far as funerals…many times deacons do funerals for Catholics who do not access to a church at the time of their family member’s death, but I have never been asked to do one for someone for say a non-Catholic.