It seems that you might be posting in the wrong forum - Trainz does not support baselines. Depending on which sim you are referring to, yes, it is possible to run a baseline using reference points from two existing baselines in the same route.
Sorry; yes I meant Baseboards, or panels. If I have a route with, say, three baseboards, number 1,2,3 can I place a new baseboard between 1 and 2, or 2 and 3?
It seems that you might be posting in the wrong forum - Trainz does not support baselines. Depending on which sim you are referring to, yes, it is possible to run a baseline using reference points from two existing baselines in the same route.
You could copy-paste the content of a baseboard to a new one and clear the old one, but that is a painfully slow process. Don’t be surprised if that takes 5 minutes per baseboard.
Take the original route and delete 2 and 3 and save as new name 1.
Take the original route and delete 1 and 3 and save as new name 2.
Take the original route and delete 1 and 2 and save as new name 3.
You can then open 1 and add a new base board, then merge with 2 and add a new baseboard and finally merge with 3.