When working with Managed Solutions, and layering them on top of each other, be mindful of one very important fact.
If you include an entity in a solution, that is also present in another solution, then the most recent solution to be installed in a system will take precedent over others when it comes to certain things such as entity forms.
For example, if you have solution A containing entity 1 and install it managed onto a server, and then later install solution B which also contains entity 1, then it’s solution B’s customisations that will be applied. If you later edit entity 1’s form within solution A and try and install it onto the server containing both solutions, the form customisations will not take.
You must always try and ensure, where possible, that each entity only exists in one solution. This would not apply if you were always going to be providing both solutions as a pair to be installed.
To safeguard, always attempt to create a new form in each solution so that customisations are carried out in each solutions specific form, and always try to avoid accidentally including entities in solutions where they don’t need to be as you can’t always roll them back due to dependancies.
Good news is that with CRM 2016, you can include only the bits you need in a solution making it easier to avoid these kind of layering issues.