How can I ensure consistency with my form lines not being on the baseline grid?

That's the rub with baseline grids — they are either/or, and if you use them, you are limited in your layout choices unless you start using exceptions and overrides, which starts to defeat the purpose of using them at all.

My first and simple advice is that while baseline grids are an asset in formal publications, with lots of text, especially in two or more columns, they are just an unnecessary and limiting option for more free-form works... and a cookbook is almost always a page-by-page jumble of paragraph and section types. I can't see making the content conform to baselines bringing anything to the final result. (You might as well decide all your instructions have to be two and only two lines long, or some other arbitrary choice.)

If you have content that won't easily fit to baselines (and again, I'm trying to imagine a cookbook where even 50% of the content does), you have three choices —

• Use the half-height baseline method (7pt baselines for a general 14pt line spacing layout), and use the half-steps to adjust things like heading and list positioning. This would be an option for your write-in lines but you'd be limited to exactly 1.5 lines. Also, when you use ANY half-step spacing, you have to use it in pairs or even multiples, or otherwise adjust things so that your bottom line on each page meets the bottom margin. (Since this is about half the reason to use baselines in the first place, you don't really want to leave half-step gaps at page bottom.)
• Set some paragraphs either independent of the baseline grid, or lock the first line only. This allows more flexibility in spacing, but again you'll have to compensate or balance the overall column height so as not to leave a bottom gap. Gets tricky.
• Be absolutely rigid in 1:1 baseline spacing and simply accept the results, esthetically and in awkward breaks.

Or just turn off the baseline grid for a project such as this and make esthetically pleasing choices for your various and assorted paragraph styles that better suit a cookbook layout. Turn baselines on when you do a novel, textbook or reference work. 🙂

Set the leading if the line lines to the double value of the baseline grid and align to it.