I can read but never understand the spoken French (language) well enough.
But I have never heard anybody mixing English with French and I am going to try it myself one day.
I do speak little Tamil and never mixed two Western languages but we mix English and Sinhala (transliterate, we call it) very nicely in spoken language.’
Now, I realize it is a talent some people have including your father and please keep improving (both languages) this talent.
Even though French will hate you for that but we who speak English will love it in spite of tongue tie and twist that it may cause us / you.
I promote Linux (computer operating system) and give bonus mark for Linux distributions with multi-language capability.
Please visit my blog site asokaplus to know about Linux and I posted a few French Phrases there and one day there will be some French Editions too, even broken French, patched up with English.
I really enjoy your wits!