(Numbers 3:4:) "AND THEY HAD NO CHILDREN." Rabbi Jacob bar Abbayi said in the name of Rabbi Aha: Had they had children, those children would have taken precedence over Eleazar and Ithamar, since whoever takes precedence with respect to inheritance takes precedence with respect to honor, provided that he conducts himself according to the custom of his forebears.
Why Nadab and Abihu's Childlessness Mattered for Priestly Honor
Midrash Tanchuma Buber, Achrei Mot 9:1
ובנים לא היו להם (במדבר ג ד). ר' יעקב בר אביי בשם ר' אחא אמר אילו היו להם בנים היו קודמין לאלעזר ואיתמר, שכל הקודם (בגדולה) [לנחלה] קודם לכבוד, ובלבד שיהא נוהג במנהג אבותיו.