Ok .... This is a bit of an odd one since I think I found the solution to the problem myself, but still need/want to know why it happened.
My goal was to create bunkers pretty much like Gary N made on the first version of Wells Hollow ...
I tried cutting out terrain and then paint , but that didnt work 100%
Then I made a clone of one of the semi rough in the layers library and then change the texture 2 to the same as the ones that are used to paint. BINGO !!! ... I thought ... All looked well at start , but after closing Unity / Reopen / Recalculating the spline the texture dissapeared and turned white ...
Got me puzzled , but in the end I made a copy of the texture , named it pebdeep 1 ... moved that to the folder : "PP Librarys/Custom/Custom Content"...and then it was all well agin ... Questions is ...Why did that happen ? ... As a designer I feel I just asseble stuff without understaning much what CF and Unity does ... and I thought I could wider my knowledge by asking this here ...