Cbillete,
This is an interesting one, as I have never come across this issue before. REFEDIT always seemed to work for me. However! I just tried to reproduce with an irrigation plan to see what type of workflow you were after and was unable to get the REFEDIT command to work! Interesting. If I REFEDIT my base plan (from my irrigation file), it seems to function just fine. I am going to need to do a bit more testing, but it seems that this is a bug within AutoCAD itself. It does not allow editing an xref in place when there are any sort of attribute or text within blocks. I know, super weird.
As soon as I am able to confirm this, I am going to submit a support ticket to Autodesk that brings this to their attention, and I would suggest you do the same. If you have any other findings that would help, please let us know. In the meantime, we do suggest opening the xref up in its own file to do your work. We understand that one of the benefits of editing in place is that you are able to see the other items in the drawing, such as planting (when doing your irrigation plan). This is why we have created a Power Tip showing how to cross reference your plans, so you can see the items needed in each drawing. Please see the link below on how to do this, and hopefully this will be a good enough work around for you. If I have misunderstood what you are after, please let me know and we can go from there.
Power Tip: How to Cross Reference Plans