Well, in Greece a senior developer is a 28+-yo bald feller that f's his m0m and is also an ugly code/idea stealer/plagiarizer from Day 1.
I'm 35 and still not considered a senior developer (although I mentor two junior guys). This is due to the fact that I get things done, something very bad in the corrupt Greek state.
i'm in a similar situation for the last 9 or 10 years. What I do is not develop anything (not a single line) with either the time or the resources of my current employer (a Greek university).
If you are involved in any kind of contract as your company's employee, don't include your IP as background IP. It is better to declare none.
Also you have to rule out all previous (if there are any) employers from any demands. You have to make clear (through a legal document) your conditions on the fair use of your IP as well as your obligations and benefits.