I am considering using miles to take a flight from LHR to the USA. It will be an open jaw, probably. LHR-SLC MKE-LHR However, my plans might change after departure. The return might move by a week, and become IND-LHR
I have enough miles to do this in Biz on UA, AA or CO. How will I get on if I try to change my ticket if it was purchased using miles? Is it better to book with AA, CO or UA.
Thanks

You didn't say if you have any status with any airline. Depending on your status, the answers and recommendations may be different.

I believe generally speaking, airlines will charge a change fee when you want to change the date of your award tix after ticketed. Routing change mostly likely is not allowed. You should check out the terms and fees under each airlines you have miles with and see which one will charges you least or give you most flexibility in terms of changes.

At least for UA, your routing sounds like a *Alliance tix. For *Alliance award tix, you not only have to call the agent to book it ($25 booking fee) but also change fee applies once it's ticketed. You may only change the dates on the *Alliance segments before departure. If the trip has begun, only segments on UA metal can be changed. The acceptable changes apply to dates only. You can't change routing. Link to UA rules: here. $150 change fee PER change with UA. However, being a UA 1K, the change fees will be waived.

Do the same research on AA & CO and see if your routing is possible.

You seem to require both dates and routing changes on this trip. If I were you, I probably will just buy the ticket to maintain the flexibility.

Good luck!

That's not the case with AA, though there needs to be award class availability to make a change. I had an off peak 40K London award booked last April that I moved to December without any cost.

If you're going to completely change airports, though, you'll need to redeposit the miles, pay for that, and try to find new availability. Don't think you'll be able to change the routing once you've started, so you'd need to make any changes before you start.

Good to know. That's why I specifically gave a UA example and advised OP to check each airline for the rules.

I never get any AA award tix with changes so didn't have first-hand experience. Without looking it up, does elite status have anything to do with no fee to your changes, Tom? That's one of the reasons I asked about OP's status since UA doesn't charge 1K as well.

I think OP has to do more research on her/his own.

AA charges everyone to redeposit miles. It's one of the UA perks I wish they would match.

Fascinating. I've been wondering if this would work.

On CO there are no fees as long as the O/D pair remain the same (even with a routing change) and the travel dates are more than 21 days out. Or if you are platinum there are no fees at all.