When DH and I were planning our wedding (which was really me planning our wedding then bringing my ideas/research to DH so we could confer), ObnoxiousBFF (who was best man -- second one at that after DH and I agreed the first one needed to be replaced) kept telling DH that he, OBFF, wanted to be our "wedding manager" (anyone ever heard of that? I sure haven't). This was his idea of "helping" -- being our wedding manager. It really meant he wanted to control every aspect of our wedding. Unfortunately for him, *I* neither needed nor wanted a wedding manager, never mind him having that role, because I wanted us (DH and me) to plan our wedding, US, not someone else under the guise of "helping" (I also pointed that if I wanted someone to tell me what to do, we would've hired a professional wedding planner). After I shot down that idea, DH then said OBFF created a spreadsheet for me to use to plan our wedding. I rejected that, too, and reminded DH I'm pretty well-versed at using Excel and already had my own spreadsheets I was perfectly happy using (to this day, I have no idea what OBFF's spreadsheet looked like).
The reason I so vehemently rejected this "help" and any other help from OBFF when possible? OBFF feels the need to insert himself as much as he can wherever he can so, even though I didn't need the help anyway, this behavior needed to be nipped in the bud. OBFF proved me right when he spent an inordinate amount of time post-reception crowing about how his suggestion of having one case of bottled water be room temperature was well-received as over half the case had been consumed. I pointed out to DH (who did acknowledge I was correct on this) that if OBFF were crowing about something so minor, how intolerable would he have been if he were allowed more input on our wedding planning? (this was the only thing that was his idea or that he was allowed to contribute)
Same thing with anything in our house. OBFF tried to foist a dining table on us that I positively hated and did not match the style of our house at all (our house was built in the 60s while this table was a contemporary metal and glass design). That table went away fairly quickly (I found a beat-up, solid wood dining table through Freecycle that I love, not to mention it fits the style of the house; DH knew the moment he saw the table and heard OBFF going on and on about how well his dining table matched the house that I was going to reject it -- DH knows I despise glass-topped tables as they are too high-maintenance for me). I let DH know early on (regarding our house) that there's no way anything from OBFF could ever decorate our house in any prominent place because we would never hear the end of it (not that it matters anyway because OBFF is not allowed into our home unless he has been sober no less than one year -- since he hasn't even managed one month on his own in the past several years, it's likely not going to happen).