LCA Part B – Use stage of 60 years

Since B stage is compulsory to be included I would like to ask similarly how deep should we dig in. Having in mind the following: B1-B3 – Bearing in mind all MEP is out of the assessment. What should be included in these parts? Can’t we just simply forget them? B4-B5 – I would assume we should input life expectancy of those materials with lifecycle shorter than 60 years. This would be for sure finishes of interiors and facades + windows/doors. The rest of relevant materials can be omitted? I understand for the credit assessment purposes this part can be different for baseline and proposed, am I right? B6 – Is this part really included? Based on the other conversations here at LEEDUser I do not have a clear conclusion. If yes should it be the EAc1 ASHRE 90.1-AppG Baseline or the proposed case? By having it in the overall credit assessment it would make the credit 10% threshold much more difficult. Is it really for sure that the B6 part (same for baseline and proposed) is calculated within the 100% resp. to be assessed within 10% threshold of the credit? B7 – Water usage is not listed in the credit relevant benchmarks. This is why I think it does not have to be included in the LCA. Am I right? Thanks for ideas/comments. Petr