I'm here!
Having brought up two bilingual children, led NCT groups for foreign parents, spent many years working in the language department of my local university that and having myself (for unrelated research reasons) read a fair wodge of the literature on bilingualism - I have to say, I am becoming less and less convinced that there really are any rules to bilingualism.
The books that tell you that you have to use this or that method (the OPOL being the most popular) invariably turn out not to have been written by linguists from research on a statistically representative sample, but by parents who have tried one method, which has worked for them, and therefore assume that this is what you have to do. I have never seen any recommendations in a work written by genuine professionals specialising in bilingualism. Linguists don't tend to do recommendations; they know too much about the enormous variability of human linguistic experience.
I learnt English as a child partly from my non-native-speaking mother (who had visisted the UK 20 years previously), partly from Sir Walter Scott. This does not mean that I have difficulties communicating with RL English people as an adult, or that I sound that like an early 19th century romance. Tush! and Pshaw!, as Cedric the Saxon would have put it.
Most people are continuously adjusting their language to their environment anyway. Most of my adjusting was done visiting England as a teenager, but a fair bit happened after I met dh. The one person I do not sound like is my mother (her English is good, but rather posh and antiquated for my purposes).
Come to think of it, I don't sound like my parents when I speak Swedish either. And dh doesn't sound like his Mum and Dad. Dd's Swedish is far more modern and colloquial than mine.
As for people telling established bilinguals that they can't possibly use the language patterns they want because it wouldn't "feel" right - isn't that for the people themselves to say? Wasn't the whole problems with the OPs friend that she tried to barge into the OPs life and tell her what to do?
Yet it's not many days since a poster on the bilingualism thread told me that I will not be able to carry on speaking both English (not my native language) and Swedish to my children as their language develops because it won't "feel" right. I pointed out that my eldest is 13, so presumably any feelings we were going to have about it should have manifested themselves by now. It is possible to have a close emotional relationship to another culture- and it's equally possible to have been born and brought up in a culture and still know sod-all about it (No dh, of course I'm not looking at you ).
Imo it's like any other aspect of parenting- it's what works for you.
From my own experience of NCT groups, minority-language mothers married to majority-language fathers have tended to fall into two groups: the ones that speak the majority language to their children despite it not being their native language and the ones that manage to speak enough of their native language to establish a bilingual household. I have never noticed any difficulties with the majority language in either case, nothing to suggest that those who have spoken English with a non-native parent are in any way disadvantaged as far as their English goes.
My best friend grew up with Finnish parents who spoke extremely poor Swedish and communicated for much of the time in Finnish. Yet as an adult, she is, as far as anyone can make out, a native Swedish speaker, who regretfully admits that her Finnish is not really as good as she would like it. Clearly for her, the influences of school, friends, boyfriends etc were more important in the long run. She hasn't got a trace of a Finnish accent. This despite the fact that she had an extremely good relationship to her parents and her father is still living. Life is a complex thing.