I am no expert at all, so take this with a grain of salt. I think that it depends on whether K-3 is required this year for a particular partnership or not.
IRS provides further details on additional relief for certain partnerships preparing schedules K-2 a...
If K-3 is not required, then one doesn't really need to worry about it as there'll be no amendment, IMHO.
For example, my limited partnership (MMP) does not do any foreign activity. Hence, K-3 is not required this year and the partnership has no plans to provide it. I don't know why they checked the box, but in the paper copy of the instructions that I received the partnership mentioned that K-3 will not be required.
If the partnership has any foreign activity, it's a different story, I don't know what the best way is, but I believe any form in the return can be amended.
