Unless you are planning to send your tickets to some central booking office you'll be dealing with airport staff who generally will have relatively little experience with owe. So it will depend more on the person than the airline. I just used BA at LAX for a reissue and had no trouble, but it was pretty much based on mutual trust. The agent wondered if I had run the changes by the rate desk and if they'd given me an add-collect. I hadn't, since it was just replacing 7 NA segments with 7 others.

So considering they have a line of people at the counter it's pretty important to smile, be nice, and understanding of their problems and you'll get what you need.

My agent did an oops and now shows the tickets valid only till the purchase date, not the first-flight date. I pointed this out to her and it was obvious she wasn't keen on fixing it. The later tickets that pass that date are not open, and I'll just carry the first bp's when using them.