More than a year ago I wondered whether Lilia & Ines would have "split personalities" based on language like I do. My guess was they wouldn't and I closed saying "we will have to ask them one day."
I have now done the next best thing: I have asked my colleague Nicolas who grew up in an OPOL/MLaH setting similar to ours: German mother, French father, born in Finland.
His answer: he does not see any difference between his German-speaking and French-speaking self.
He picked up Swedish, English and Spanish later, and he does feel differences when he speaks those languages.
The real question is: while my daughters won't be different when they speak another language, will they notice that I am? And will they use that knowledge? Will they use German when they ask a favour?