Look at the pinned server configuration options post and towards the bottom of that post Olympia explains how to adjust the spawn weight multipliers.

if you are speaking of where it says how to change the spawn weight multipliers DinoSpawnWeightMultipliers=(DinoNameTag=ParaNest,SpawnWeightMultiplier=10.0,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.01)

ive used these before on creatures but i tried using this with the new tag that was given to the survivors and it didnt seem to make any difference still super rare and i cranked it way up to test if it was making a difference
i did a quick fly around the highlands and desert on rag didnt see a single fallen survivor

what code should i be using and where exactly should i be putting it
any help is appreciated thanks for responding :)