At the very least the cost could be split into 1. actual cost 2. guesstimated additional cost of 'very hard to split X'. So that people looking at the accoun

At the very least the cost could be split into 1. actual cost 2. guesstimated additional cost of 'very hard to split X'. So that people looking at the accounting many degrees of separation removed will still be able to understand which is which and the relative proportion.