I have used sections from user table for modelling. Now is it necessary to create individual tapered members where the purlins are being placed or is there any other options?
The rafters would have to be split at the location of the purlins for proper connectivity and load transfer. So before you assign your tapered cross sections, it would be better to generate the wireframe model so that you know where these rafters are split. Subsequently you can define the tapered sections for each of these segments. You just need to know the depth at start and the end of each segment and use the Tapered section input as shown next
Input through user table is fine too.