You people need to grasp the concept of dissociation in aqueous solutions, equilibriums and solubilities, then these questions would stop.
If you pour HCl into an aqueous solution of K phosphates then you end up with a solution of H+ and K+ cations and all kinds of phosphate plus some Cl[sup-[/sup] anions. You cannot magically separate them and selectively remove one and only one component.
There is no H3PO4 in solution, and neither is there KCl in solution since these are dissociated. If KCl will precipitate and KxHyPO4 stay in solution or the other way round depends on solubility products.
The concept of stronger acids forcing the weaker acid to be protonated is an academical curiosity when both acids are strong, and I could give you several real world examples where the weaker acid is forcing the stronger acid out of the mixture, since other factors like solubility, boiling point etc. become important.