Vesting is ok, but it is, at best, an attempt to patch a fundamentally flawed tradition in equity allocation in which chunks of equity are granted at the outset of a new venture in anticipation of future contributions. When this is done, anxiety (like you have) immediate sets in.
A perfect solution will easily accommodate the variability of commitment levels of individual team members, it will be flexible over time as things change, and it will ensure total fairness for all those involved.
I've developed a model, called Slicing Pie
, that guarantees that each person gets what they deserve to get. It is a dynamic equity model meaning that it changes over time to keep it fair. There are two parts.
The first part is an allocation framework. The model allocates equity based on the fair market value of the contributions times a risk multiplier. Fair market value is important because it is an observable indication of what each person puts at stake. This is, in effect, their "bet" on the future of the startup.
The second part is a recovery framework. It will determine the appropriate buyout price in the event that someone leaves the company. The price will reflect the contributions they made and the nature of the separation. Getting fired, for instance, is different than getting laid off.
I've written several books that detail how to implement the model and I would be happy to give you a copy if you contact me through SlicingPie.com.
Also, here is an infographic on the basics of the model: