Question: What does Jewish Law say about funerals and mourning rituals during Passover?
Answer: In terms of such a loss, it is your Rabbi who should guide you. No one else, including other Rabbis, should interfere or contradict your Rabbi's opinion and ruling.
Traditionally, the funeral is conducted during the Intermediate Days of Passover (called "Hol HaMoed" in Hebrew). Under certain circumstances some Conservative Rabbis will conduct the funeral on the second day of the festival.
Traditionally, one would not sit shiva or observe the traditional mourning rituals and customs during the week of Passover. Shiva would begin after the conclusion of the Festival because Hol HaMoed days are not completely "ordinary" or "profane" days but have some a festive element to them.
Knowing that (1) this is truly an imposition on the natural inclination of human emotion, (2) that modern Jews encounter major issues of logistics, widespread family; (3) Jews today very often make their own choices for convenience rather than turn to their Rabbi, - the Committee of Jewish Law and Standards of the Conservative Movement in 1977 offered and unanimously adopted another option.
It is recommended that there still be no formal shiva during the Intermediate Days or on the concluding Festival Days. However, if people happen to visit those in mourning on these day, then they would be welcomed minus the signs of mourning.
After the conclusion of the final day of Passover, the mourner ("avel" in Hebrew) should observe at least one whole day and a small amount of the next day of formal mourning. This would mean that together with the last day of the holiday (an additional day that was added only in the Diaspora for calendar communication reasons 2000 years ago), the mourner would observe the critical first three days of formal mourning.
The mourner should be advised that for the next additional days which according to tradition would have been considered formal mourning days, the mourner should try to practice the public modest elements of mourning out of respect for the loss and the community.
With best wishes,