Your sample data won't load. The last row for logins is invalid, not a huge deal I just skipped it.

However, the rows for [ProposalProfitSplitWorksheet] all fail the foreign key constraint for logins. I really need you to test your inserts. Keep in mind that we are all volunteers around here and all the time I spend messing around with being forced to turn identity insert on and off so I can insert identity values and messing around with poorly formed data and syntax is all eating into the time that I can spend on your actual issue.