try this in a button:

let t := this;
for loop1 in JOB do
    for loop2 in loop1.CONDO.OWNER do
        let newRec := (create SPLIT_JOB);
        newRec.(
            SERVICE := t;
            CONDO := loop1.CONDO;
            OWNER := loop2;
            ITEM := loop1.ITEM
        )
    end
end

Instead of linking by ITEM in SPLIT_JOB, link by JOB. Then you can get ITEM and SERVICE without having to create multiple links.

You can also make SPLIT_JOB a child of JOB, maybe call it OWNERSHIP_SPLIT and create a record for each owner so you can do the ownership math there.

Just thinking out loud, but maybe you want Price in JOB to be a number field that the data is copied over from ITEM but allows you to change it per job and will not update when you change the price next year or two years. This could also apply to other data that you want static per job.

May I ask why CONDO is linked in Jobs not in Service? Seems like you create a Service record, record the date and condo that needs the service then add the jobs related to that service.

You can put the code of the button in the Trigger after update in the ITEM field in JOB or in the Trigger on new record for the JOB table (if you move CONDO to Service).