How do I model SS ex-spousal benefits with future marriage after age 66?

My domestic partner of 17 years and I both filed for divorced ex-spousal Social Security benefits this year. Hers is $1,113/month. Mine will be around $800/month. We are both 66 years old and plan to switch to our own 32% higher Social Security retirement benefits when each of us turns 70 in 2020. I am retired and receiving a small pension and doing Roth conversions, while she is still working full time and intends to work through at least 2017, possibly longer. I have another small pension that I have not signed up for yet that grows by 10%/year delayed retirement credits. We originally thought we would wait until 70 to marry to maximize our Social Security benefits but are now leaning towards marrying in June 2017 when we will both be 67. We are considering this because we read Kotlikoff's 9-21-2015 PBS Newshour column indicating that those who marry can continue to receive ex-spousal benefits if they marry someone who is drawing on other than their own SS retirement benefit, which would include both of us. I am not sure how to model this in EsPlanner Plus. I would like to compare the difference between marrying at 67 vs 70, as well as tradeoffs of pulling from retirement investments vs 2nd my 2nd pension if she retires before 70. If we marry at 67, once she turns 70 in January 2020 and starts drawing her own 32% higher SS benefit (@$2,237/month), would my ex-spousal benefit stop? We don't want SS to backdate hers 6 months. Would I then refile as a spouse on her for 4 months until I turn 70 in May 2020 and then switch to my own 32% higher SS benefit (@$2,943/month)? If I understand Social Security correctly, if either of us or our respective ex-spouses die after we marry, either of us could draw on either our current or past spouses as widows for which ever benefit is highest since we will remarry after age 60. Thanks on any feedback on how to model this in EsPlanner Plus.