Add new property from plugin without overwriting class

Hi guys,
I looking to create plugins to add some properties to Objects. To make it more readable and clean I decided ti split those plugins into several plugins. I looked on official plugin and they just overwrite existing model/custom object with the new one. This will properly works if plugins don't add properties to the same Object but if not, it will create conflicts. Indeed if I install one plugin then add the other one, the second one will overwrite the previous modified object. To counter that each plugin needs to take into account all other plugin's cutoms properties and plugins will have to be installed in a specific order which is pretty bad.
Have you guys encounter this problem? Did you find a way to dynamically add field to the existing cutom object?
Thanks a lot,
Antoine

Okay thanks. Well we don't use this plugin because it's not a free one haha
Bye,
Antoine