Hello,

I have a doubt on the use of interrogative polite forms like:

Could I ask you...
Do you mind if I ask
Would you please be so kind as to tell me
May I ask you
I wonder if you'd mind telling me...

The doubt is this: can these form be followed by the inversion of subject and verb?
For example: "Could i ask where is the museum?"
"Would you please be so kind as to tell me if what time is it?

I have a memory of a grammar rule in which in a sentence there can't be more that one interrogative structure, do I remember well?
Thank you