GPX route with alternative sections

Hello,
There are situations where a given route for a certain section has a different course (alternative). At this point we have to trace two routes.
While riding we use one, but when we want to use the other we have to switch to the alternative route.
And here is the problem.
On the website of the cycling association in Bielsko-Biała (PL) I found a cycling route that had alternative sections in it. To be honest, it is a great solution, because then I do not have to create several routes in GPX.
There is only one problem - we will not do it in BRouter or Locus Web, for now.
Hence the idea: maybe do it in Locus Web - it would be a real hit!