Sound advice needed for tweeter Install in a MK6 Fiesta

Hi everyone!  I hope y'all having a grand day! :)

I just bought myself two pairs of InPhase Component 5x7 speakers (with crossover and tweeter) for my 2006 MK6 4 door Fiesta Style.

The car has never had any tweeters fitted so I would like to know which methods you guys and gals have used to install the tweeters. I'd like to do this without cutting any new holes if at all possible.

For the front tweeters someone told me that they can be placed behind the little triangular air vent on each side. The vents which are just above each of the main round air vents nearest the doors. I'm assuming this would mean dismantling part of the air flow system. I dont think those little vents do much anyway do they? Or... I was thinking that if some of the MK6 models come with tweeters fitted as standard in places like the A-Pillars, door trims, dash facia or where the door mirror adjustment levers are, then where could I purchase some from?

And where to install the rear ones?

Any help would be greatly appreciated.

Many thanks in advance. :)