I have changed dates/cities multiple times on tickets that had expired SWUs applied to them without issue. As mentioned by others never mention they are expired or admit that they are, you just want to remind them that SWU upgrades are applied and you want them to carry over (in case they somehow don't see them).

The question I had is if I can do a same day change on the domestic outbound without it impacting the rest of the ticket (for example ORD-JFK-LHR doing a same day flight change on the ORD-JFK flight)?