UI redesign rules

[humble_learner]

There is an application that encompasses many other small applications (which are separate exes). The main application is used to only instantiate the other small applications. The other applications are somewhat related to each other and ended up being individual exes because of over time independent development.

Would it be a good idea to go with the independent executable method (as the original) during a rewrite to a modern technology or would it be better to have a single application (main frame for example) which encompasses the other applications redesigned as child forms ?
I am afraid of violating GUI design rules as regards cluttering an application with too many forms, child forms and sub-childs etc.

Do let me know your views on how to approach such a problem.

[boudino]

Are there any extra other services expecting that there are particular .exe which they runs, or it is just a single application used only by human users? If so, I would keep separated functions to independent units, but prefer assemblies (dlls) instead exes, which enables you for example to expose the services trought WCF.

Advise you something about the structure of the GUI is hard, just try to keep it simple and keep it detached from the particular services. I'd try to end with something like single exe which host individual gui - control forms of particular services, and individual services (former bunch of exes) controlet trought the associated screens.