I asked both my financial planner, and paid the Turbo Tax expert to go over my return last year, and both said that it would be fine to simply claim half of a big RRSP contribution last year, and the other half this year. Neither said that I needed to claim the whole thing and carry forward half. I specifically asked the Turbo Tax expert this question, and he said no, I could simply claim the other half this year.
To report any contributions you may have missed claiming in 2017, you do need to make an "adjustment" to that return. You can use "My Account" if you are set up, otherwise, you will need to print a paper copy and mail it to your tax centre.
However, here's a way that those contributions should automatically be added to your 2018 without making that adjustment! If you use CRA's Auto-Fill service to import your tax slips, these contributions should be in CRA's records and will be downloaded to your return as a "carried forward contribution" which can then be claimed on the current year tax return.
Thanks for your answer. I have done the auto download from CRA, and it is not showing up. I've tried a couple times....and Turbo Tax crashed and erased half of my return. There seem to be glitches in the product this year, sadly. I will have to change last year's return, I think.
When you go to make the adjustment online, "if" the RRSP is there (and it should be), if it is listed as an "unclaimed contribution", you should be able to just apply it to this years return as an "unused contribution". Only if that RRSP is NOT there with CRA will you have to make the adjustment. And usually online adjustments are processed very quickly, so hopefully this doesn't hold you up from filing for too long.