When I am inquiring about an offer in store, there are some add-ons that are not included in the plan. Should I use on or in with "the plan", saying:
Is there any free add-ons on/in this plan?
And in another situation, like when I am telling someone that he will be included in my work or project plan. Which should I choose, telling him:
You are in/on my plan?
If these two situation have different choice, is there any reason for that?
Best Answer
With regards to project documentation, "the plan" could refer to two things:
For example, a particular diet may be outlined in a document such as a book. You would speak of details being in a book, yet someone who was following it would be on the diet.
Likewise I believe you would speak of details being in a written plan (such as a project document), but once the plan was in effect you would speak of things being on plan to mean that you were still following the plan, or things were going to plan.
In your other example where "plan" is used to describe something like a mobile phone contract, you would almost certainly say "on" the plan if you were referring to anything inclusive in it:
But in your example you specifically talk about "add-ons", which by nature are extra to a plan. So if you were asking about anything extra that may be bundled if you took a plan, you might actually say:
Because the the add-ons are not part of the plan, but you might get them as well.
Your last question:
Refer to the first part of my answer. If you are referring to the plan as an entity in itself, either the document or the concept, then you would say something is in that plan. But once the plan is up and running then you are on that plan.