Nested ticketing is only prohibited where it is done to avoid fare rules.
E.g. I want to travel to XYZ to work four days a week and be home for three. But the fares are much more expensive if I do this; cheaper fares include Saturday overnights. So I buy "nested" tickets that start Monday of week 1, return is Thursday of week 2, etc. (If I were smarter, I'd buy my tickets as return tickets home, including the Saturday night stay; I might buy singles to bracket, or even buy a return flight or another airline that brackets the job duration - legal and meeting the terms and conditions, and pretty much not a red flag to revenue protection folks. Hmm, I may have done this when I was a road warrior... having difficulty remembering.
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Or I buy two return tickets that bracket each other. Those are clearly an attempt to evade fare rules, and AA may catch this, mess with my plans.
But let's say I have a trip scheduled to ZYX with a duration of thirty days. Minimum stay is seven days, maximum sixty. Whilst there, I find I need to travel to ABC for a few days to service another client, so I buy a return ticket that complies with the fare rules. Perfectly acceptable.
In your case, it might be quite reasonable to change your ticketing. Of course, depending on your current fare rules, that could incur change fees as well as repricing costs. It may well pay to check it out to save some money, time and flat tire depressions on your butt.