I have created few objects for P&I. Unfortunately i have encountered some problems with them:
1- Autocad dinamic dimensions don't seems to work in Plant (I can't see the grips, even if I create the blocks with Plant)
2- The custom blocks don't align long the pipe direction (I insert the AttachmentPoint1:EndCode0 and AttachmentPoint:EndCode1). Some of them to get the right direction I must first insert them, and they don't turn, then I have to move them and now they turn properly.
3- If I insert an inline custom object it trimm the pipe line properly only in the direction of the original block drawing, if it rotates it trimm the pipe line as if it is not rotates. (img. attached)
1, Dynamic blocks do not work in P&ID, you can use dynamic blocks but the dynamic information is lost when converting to a p&id block.
2. Did you try "AttachmentPoint1:EndCode0" and "AttachmentPoint2:EndCode180" vs 1
Not sure if 180 vs 1 makes a difference or not but may be worth a try?
3. sorry no idea on that one.