@Shannon, you can't "add" it to your order. They have added new reward levels that you can switch to.
I don't see the 3 or 5 packs to add to my order...what am I missing?
Are they motorized in the 3-pack?
While KS only allows you to pick one reward level, you can pledge as much as you want. It is common for a project to allow people to pledge additional money to combine rewards. For example, on one project, my reward level was $25, but my pledge was over $150 so I could add all kinds of extras. The extra work is on your side, keeping track of what people are actually buying.
You could allow people to add a manual kit for $43 or a motorized kit for $76, if you wanted to.