First confirm with your finance team whether you can take the balances in the source currencies as starting values, or if you can open Dec 2025 and post the balances there to keep YTD 2026 clean. That's the simplest approach and it does reflect the state of ENT25 at the end of its use.

If you need to take all the journals and since ENT087 is new, you could go back and open ENT087 for the first period where ENT25 was used. Enter the journals for that month and close, including revaluations and such, confirm that the results are the same as in ENT25. Before closing, do a quick check that nothing else managed to get into the period while you were processing; the risk is low but not zero so it's best to check. Repeat for the other months that ENT25 was active. If all the rates remain the same, it should come out the same. ENT087 will then be an exact copy of ENT25 as of the end of December.

As always, test in a test instance first. Confirm all the figures. If anything comes out different, then you will need to discuss whether adjusting journals can effectively get it to the correct amounts. If they can, then repeat in production, including any adjusting journals, during off hours to minimize the chance of anything else landing in the prior periods.

If there are differences and adjusting journals aren't feasible, then post here again so we can help further.