I have the opposite problem; I would like to NOT claim the Canada Caregiver Amount on my father's return (i.e., I don't want him to claim the credit for my dependent mother), so I changed the line "Do you choose to claim the disability transfer (if applicable) from your spouse" on form INFOWS from yes to no; however, line 51090 on schedule 5 remains set to 2230.
The line "Is your spouse dependent upon you because of a mental or physical impairment (Canada Caregiver Amount)" is already not set to anything. I set it to no just to see if it would make a difference, but it did not.
If I try manually override 51090, then I get a warning that says "If you override this calculation, you cannot file this return using netfile". Is there a way to not claim the Canada Caregiver Amount for a spouse, and still be able to file using Netfile?
Edit: I seem to have found a way; say no to "Are you eligible to claim the spousal amount?" on form INFOWS.