I disclosed a patentable concept to my employer and some other colleagues who were tasked to evaluate technical feasibility, they try to instead propose "improvements". This is despite sending them a broad description of the concept and not all the alternative embodiments so likely their "improvements" may be included in the final draft anyway. It is very likely that they don't know about patenting and that I am trying to patent something as broadly as possible rather than getting into several permutations or specifying minor improvements which probably would not stand alone as substantial patentable improvements. Do you think they are trying to get a place in the inventors list and how can I prevent this? If unavoidable, is there an established process of having different ownership percentages in the patent?
There are several issues here. If your invention is part of your job or you are otherwise required to assign it to your employer then it will be owned by your employer and the listed inventors will just be a matter of pride not ownership or monetary value. This is a very likely case.
If it is your IP and not that of your employer, I hope you have disclosed it under an understanding of confidentially. If not you are now barred from filing in the most of the world and have a sort-of one year grace period to file in the US. If your claims extend to anything suggested by your colleagues you may be obligated to state that in a disclosure to the USPTO.
In the US all of the listed inventors on an unassigned patent have identical and undivided rights. They can all license third parties with no need to account to each other. If they chose to have joint ownership under a less horrible set up they can all assign their rights to some entity and share rights in that entity in any mutually agreeable way assuming they have no preexisting obligations.
Inventors are those that have made a conceptual contribution to something that is claimed. If it does not belong to your employer and you are controlling the prosecution you can cause there only to be drafted claims to things where you are the sole contributor and you will be the only inventor. If others who you disclosed your invention to decide to file separately on the improvements they have made you will be in a very complicated situation.
Second, I suggest, you present the general concept and all the possible applications you can think of next time. If you share all what you have, it won't hurt you that others improve your idea. It might be the case that you may file 2-3 patents instead of only one.
Also, don't forget in most cases royalties are dependent on the success of the invented product. It is financially better to be a co-inventor of a widely used product than the only inventor of a never sold product.
First thing to remember is that if you work for a company they own the results of your labor and that usually includes IP. So, it is very likely the company will own any resulting patent. Thus, there is no issue with ownership percentages.
As for additional improvements, identifying alternative embodiments is a good thing and can result in a better patent. The patent attorney will determine if any of those improvements result in a claim and thus the person suggesting the improvement being listed as an inventor. Having co-inventors does not diminish your status as an inventor.
In my opinion, your professional life will be more rewarding if you collaborate with your colleagues and look upon their contributions as helpful. They might get added as an inventor on your patent. Down the road, you might contribute to one of their inventions and become a co-inventor too.