Simplifying a little, I do this by letting combinations of case markers reference their foregoing nouns, like pronouns.
1. What does that look like in simple examples?
Here in SOV using case suffixes and freestanding pronouns, "referring" case first so it reads kind of like "the ACC object is the NOM up next." You can rearrange that sort of thing.
Fred likes trees which lean.
Fred-NOM trees-ACC like ACC-NOM lean.
Fred points toward trees which lean.
Fred-NOM trees-DAT point DAT-NOM lean.
You don't necessarily need the first -NOM if the subject is always first.
Fred owns the horse and kicked Bob.
Fred-GEN the horse-POS owns, GEN-NOM Bob-ACC kicked.
Fred owns the horse that Bob kicked.
Fred-GEN the horse-POS owns Bob POS-ACC kicked.
Fred owns the horse that kicked Bob.
Fred-GEN the horse-POS owns POS-NOM Bob-ACC kicked.
2. What does that look like for my example?
You saw the person whose killing by someone I hated.
You-NOM person-ACC saw, I ACC-GEN killing-POS someone-ERG POS-ACC hated.
3. What if I have multiple objects of the same type?
For me, the case particles also "and" by repeating.
Fred likes trees and buildings which lean and which stink.
Fred-NOM trees-ACC buildings-ACC like ACC-NOM lean [ACC-NOM] stink.
If a verb always comes last, you may not need the second 'ACC-NOM' to "and" there. A "zero-and" was an emergent behavior from my syntax which I love.
The speaker should decide whether the intended antecedent is clear in context...
Yuki teaches Japanese and Javanese, which is uncommon in Tokyo.
Yuki-NOM Japanese-ACC Javanese-ACC teaches, ACC-NOM uncommon Tokyo-LOC is.
... whether you are better off with two sentences or a different tool (a "verb case" for this and other non-finite verbs? a pro-verb to refer to a verb?)...
Yuki teaches Icelandic and Javanese, which is uncommon in Tokyo.
Yuki-NOM Icelandic-ACC Javanese-ACC teaches. Teaching-NOM those subjects-ACC Tokyo-LOC is uncommon.
Or perhaps use word order to link by proximity. Below there are two different "locative objects." Context might already tell the listener that "they" can't take "the day." Still each appears closest to the clause where it is relevant.
The day on which the Storm-God thundered furiously, the chariot on which I stood on that day, they took it
The day-LOC the Storm-God-NOM thundered furiously, the day-LOC I-NOM the chariot-LOC stood, they-NOM LOC-ACC took.
4. What does that look like in a more complex example?
Alice sees Bob, who points at Charlie, who runs from Alice, who is Bob's neighbor and boss.
Alice-NOM Bob-ACC sees, ACC-NOM Charlie-DAT points, DAT-NOM Alice-ABL runs,
ABL-NOM-POS Bob-GEN neighbor ABL-NOM-POS boss is.