How can I see the number of miles required to upgrade an economy class ticket with a stopover in DXB to business class?
Is it the same price as for a booking without a stopover, or are the upgrades calculated per segment, which would be much more expensive?

Background information:

I'm trying to book ARN-DXB-BLR for myself +1, but for I want to fly a week earlier than my +1 and have a stopover in DXB, and then we will continue to BLR together.
When I search for ARN-DXB-BLR without a stopover, the EK website immediately offers an upgrade to business class and I can choose eco flex/flex plus and see the respective number of miles needed.
However, when I use the multi-city search with the stopover for myself, there is no mention of an upgrade.

I called EK and they said that no upgrades are available at the moment. Which doesn't make sense, because website explicitly gives me that option ("But it will not be possible to apply the upgrade, Sir"), and I can even book an award flight directly.

I would simply make the booking and try it for myself, but EK said they only offer free refunds for ex-US flights. And I only want to fly it in business class - otherwise I would rather choose a different carrier.