How-To unique schema markup in collection page

I need to add to the blog a unique schema markup to improve SEO.
The guideline explains well how to add it to a page with basic schema such as blog post or a static page,
when it comes to an How-To schema this is no longer relevant.
each How-To page has different number of fields and making one schema in the template is not possible, some fields would be empty in some of the pages and it would lead to an error in the page’s schema.

for example, some How-To posts would have 8 steps, while some would have only 5 steps.
If the template’s schema would be include 8 steps, some pages would have 3 empty steps with no data in the fields, and it would throw an error.

How To Schema resource:

I couldn’t find any way to go around it, other then migrate the blog to a different CMS