I have had to eliminate P&L accounts to the BS on a number of occasions. In fact, I seem to have to do it at every build lately.
I'm not an accountant by training, so I apologize in advance if my description sounds confusing for trained accountants. At the end of the day, it's just adding and subtracting. ;)
The root of the problem is that the NetIncome, being a schedule, gets rolled into the Retained Earnings BS_YTD_NI account. That's not an issue for P&L accounts that eliminate within the P&L, as those will have no overall NetIncome impact.
When eliminations span between the P&L and BS, that will impact the NetIncome. As such you need to eliminate the P&L account, and similarly the portion that rolled into BS_YTD_NI. But if both the P&L and BS_YTD_NI account share the same Plug account, you will double eliminate one side of the transaction, resulting in the Elims being OOB. The simple solution is to configure the P&L or BS_YTD_NI account to use a dummy Plug account that resides outside of the BS, so you are only eliminating the P&L side once, and performing a second one-sided elimination.
Another problem you can run into is if you strip off IC detail when rolling the P&L data into BS_YTD_NI, which will prevent the elimination from occurring in BS_YTD_NI. In this situation the Elims crossing between the P&L and the BS will balance, but the post eliminated data will be OOB, as the BS_YTD_NI <> the P&L (P&L got eliminated but not BS_YTD_NI). If you are eliminating between the P&L & BS, the BS_YTD_NI needs to retain IC detail, but only for the P&L accounts that are to be eliminated to the BS.
I can't emphasize the last part of the prior sentence enough. When rolling the P&L to the BS_YTD_NI, you must only include IC detail for the P&L source accounts that are to eliminate to the BS. Otherwise, you will be double eliminating data in BS_YTD_NI that eliminated within the P&L, throwing those Elims OOB. You need to write a data buffer handler to figure out what IC data to keep/ditch when rolling the P&L to the BS.
If you have multiple plug accounts crossing between the P&L and the BS and choose to tag the BS_YTD_NI accounts with the real BS plug accounts, then you will need a BS_YTD_NI account for each BS Plug account, as you can only assign one plug/account. If you want to roll all P&L IC detail to the BS_YTD_NI, you need to make sure the P&L IC accounts roll to a BS account not having a Plug.
I run into the same need with NCI/partial ownership.