You are confusing yourself..
In K.P, any planet will first signify the house occupied by its consellation lord, then the houses owned by that constellation lord (unless that lord is rahu/ketu), then the house occupied by itself, then house(s) owned by itself (again unless that planet is not rahu/ketu) as they dont own any house).
Now if you have a case of any planet conjunct with Rahu/Ketu, then you want to know how they behave ...
I'll try to explain with one example.. Rahu in sravana-4, conjunct with Mars in Dhanishta-1 in makara rasi (7th house). These two are aspected by Mercury conjunct Ketu in Aslesha-3 and Aslesha-2 (1st house) respectively.
Rahu is also an agent of Saturn as makara owned by it.
Now Mars is own star in 7th house strongly signified 7th house, then 5th and 10th Houses. Mariage did not happen during mars dasa though that person was in age 20-27 during that dasa.
Later Rahu started at 27 age and continued till 45th year (18 years).
During this, Rahu performed marriage during Mercury Bhukti.
Why ? Rahu in moon's star (moon in 10th, owner of 1st) is not supposed to give marriage as easily as Mars.
But here Rahu conjunct Mars has taken over Mars duty, being in Saturn house (7th lord in 11th), and aspected by Merc+Ketu.
Ketu became more powerful as it was conjunct Merc and in merc owned constellation.
Ideally Rahu dasa, Ketu bhukti should have done it, but transits didnt match during that 1 year.
Infact they matched perfectly during Rahu-Merc dasa with Saturn in aslesha, Jupiter in Jyeshta, Sun in Mithuna rasi, Moon in Revati nakshatra, day being saturday (night), lagna being Kumbha with Rahu in it (rahu in satabisha).
So Rahu-Ketu took over everyone else and performed the event