Apart from an earlier feeder flight (which may be a PITA, given an OTA booking), there are good reasons to get WCHR support:
- The wheelchair pushers tend to be nice and eager to help people.
- In IROPS situations, you get priority treatment for rebooking, overnight, care, etc (mandatory according to EC261/2004 regulations for people with disabilities). Which may also imply your replacement booking may become less wild/cumbersome and more direct. When you look capable to judge, you will be asked whether the proposed solution will fit with your disabilities.
- Even when your folks are still walking capable, it goes slower, implying, you gain 5-10 min for door2door for the walking part, with a wheelchair. Given the airport size, I don't expect a buggy at CPH.
- At security/immigration, you get dropped right at the counters, implying, you can easily gain 5-10 min, compared to queuing like ordinary people.
- Wheelchair pushers know their way around the airport, implying, direct routes and avoiding busy bottlenecks, when possible, know where the elevators are and be able to use these.
- Because you have (2) wheelchair pushers, they "know" where you are in the building, which makes it easier for the gate staff to hold-on the wait just a little longer.

WCHR needs to be requested direct from the airline (not the OTA), they do have dedicated sections on their website, how to submit the WCHR request. Some airlines (CX) do have the opportunity to book WCHR just online in the manage booking portal. Sometimes an explanation is requested, in which case a phrase like "can not walk long distances and not stand up for a long time" will be the secret answer. In Europe, the WCHR services itself are provided by the airport.

WCHR does also have its drawbacks: No seating at emergency exits seats.