Sweden adds a new requirement for entry:
My husband and child are traveling back from (Oslo) from Tenerife (where my family lives):

• TFS-ARN 2Jan landing 00:30 past midnight
• ARN-OSL 3Jan

The flights are with SAS, bought through Expedia.
The new entry rules for Sweden ask for a negative Covid-19 test when entering the country, regardless of your vaccination status (less than 48 hours old). This started Dec 28.

It is not possible to produce such test, this weekend is not functional in Spain:
The problem is that Tenerife cannot provide those tests, because this is the New Years weekend and a weekend. We were unable to locate viable test facilities yesterday (Jan1) and will try again today. To make things worse, both airports have stopped offering tests as they are in the process of changing from a lab provider to another, and one finished before this holiday weekend and the next one is picking up the service next week. We have checked all the centers in the lists given by the airports, there is no viable option, we will lose those flights today and airport personnel told us yesterday lots of people missed their flights for not being able to secure a test to departure.

Our current plan:
We bought them flights for Jan 3 directly over CPH so that they can get back to Oslo (this time directly with SAS). We called Expedia and SAS and they were allowing us to change our flights, but at full cost of purchasing brand new one way flights, so we actually purchased brand new one-way flights to have the 24 hour money-back guarantee.

We will visit again both airports today to see if by any chance the new company in charge of tests at airports has started (no one could tell us yesterday, their offices were empty). If we can get a test, they catch the flight tonight to ARN. If there is no test available, we have the backup flights for tomorrow, 800EUR for both of them.

Advise from expert flyers:
Since it is impossible to produce a negative COVID test this weekend in Tenerife, I believe the re-routing should be offered by SAS or Expedia. None of them thought so on the phone, they offered us to change tickets paying the same 800EUR, and voiding any money back guarantee since it would be a change and not a new purchase. They did not consider this a necessary change, even if the passengers cannot use the flights due to circumstances out of their control (entry rules change and black out weekend for testing in Tenerife) and treated it as a regular flight change request. I believe this is a necessary change.

We have bought the new one-way flights for tomorrow so that we can get this kid back into school in Oslo, and will try to request our money back arguing that this is not a regular change on flights requested by a passenger, but a necessary re-routing since the transit country changed rules that cannot be met, and unfortunately due to the timing of their flights they needed to "enter Sweden" that night en-route to Sweden. I would like your input on this:

Any advise on whether we have any rights for making this argument? any previous case of destination changing rules and airline leaving you on your own? any input will be very appreciated.

[Mods please move to other sub-Forum if more appropriate]