Five crosses - high altar panel with relics

A “panel with a central oval” was inserted in the 16th century in the frontal lower part of the high altar of the S. Maria della Passione church in Milano, Italy. The altar cavity in oval shape located in the central panel contains relics and is adorned with gold gilded symbols of the passion. Inside this cavity are relics of the saints presented in small glass containers and identified with written documents. Question: Did this individual central panel with cavity for the relics require 5 crosses for the high altar to be consecrated in the 16th century? Did the imagery of this panel require sacred imagery? Is the cavity a sepulcrum?? ![The high alter with panel of Santa Maria Della Passione ][1] Please view the image of the high altar and panel on the YouTube video "[MILANO, la meravigliosa chiesa di SANTA MARIA DELLA PASSIONE](https://youtu.be/PVhw393Bdno?t=541) " at minute 9:04.