This query:

select p.file.fullName, score
from familyPhotos p
let score = IFMISSING(p.ranking.scores.emma,0) + IFMISSING(p.ranking.scores.matt,0) + IFMISSING(p.ranking.scores.ali,0) + IFMISSING(p.ranking.scores.matthew,0)
where score > 0
order by score asc, p.file.fullName asc LIMIT 50;

Generates this recommendation:

CREATE INDEX adv_ifmissing__ranking__scores__matt_, 0_ifmissing__ranking__scores__matthew_, 0_ifmissing__ranking__scores__ali_, 0_ifmissing__ranking__scores__emma_, 0 ON `familyPhotos`(ifmissing((`ranking`).`scores`).`matt`), 0),ifmissing((`ranking`).`scores`).`matthew`), 0),ifmissing((`ranking`).`scores`).`ali`), 0),ifmissing((`ranking`).`scores`).`emma`), 0))