Any chance you found a solution for this? It's obvious the pipeline that the solid belongs to isn't completely lost when you create the solid, as it still shows the solid pipes under the correct pipeline when you look at the Pipe Solid Manager. It seems like it should be a simple solution.
Anyway, I came up with one, but it's not the MOST optimal.
When you're creating pipe solids, you let them take their default names, with the pipeline name at the beginning of the solid's name. Then set your repeat region to asm.mbr.name. Then go into your repeat region's relations manager. Add a custom parameter below the relations window (I called mine "PL"). Then just use an EXTRACT() function in your repeat region's relations to pull characters from the pipe-solid's name. If you use the same function for multiple different pipelines, you just have to change the EXTRACT() arguments to adjust for the pipeline name's length (in characters). OR, if you know you'll never get into the thousands of pipe solids per pipeline, and you never use zero's in your pipeline names, you could use SEARCH() to look for the first zero in the pipe solid's name. Get creative with your string functions.
Examples (I commented out the first one as I'm not using that in my model) :
Then you just set your repeat region to rpt.rel.PL
Here's a list of string functions you can use (Page called "Operators and Functions for Strings", in the Creo help files, in case the link ever gets broken.):
http://support.ptc.com/help/creo/creo_optm/usascii/index.html#page/optm/options_modeler/fund_seven_sub/Operators_and_Functions_for_Strings.html
