Error with simple links to other files

[Expiry]

I'm working in a new office and I have a problem that I've not encountered before.

I have a destination file which has links (sumif and vlookups, mainly) to more than one source file. When I open the destination file, the values are there and everything is fine. If I open one of the source files, the links for that file update as expected, but the destination file also tries to update the links to the other source files, that aren't open and because it can't find them, all the previously held data is replaced with #VALUE.

I then have the labourious task of having to open all the linked sheets in order to replace the values that were there before.

Anyone have any ideas why?

 

[Expiry]

I think this is a problem that no-one can solve. Which means I've not failed, probably.

 

[Expiry]

Still not found a solution to this. I'm really flummoxed.

Anyone help?