Shouldn't this be done using a loop to go from the first one to the last one checking if the point is inside each rectangle?
Given that your point to be checked is Xp,Yp and you have n rectangles defined by 2 points in a plane (XY): Xr1[n],Yr1[n], Xr2[n],Yr2[n], shouldn't it be as easy as something like:
This is pseudocode to achieve that... probably it is too simple and I've not understood properly your question...
bInsideAllOfthem = true;
while bInsideAllOfthem and n <= number_of_rectangles
bInsideAllOfthem = ((((Xr1[n]-Xp > 0) and (Xr2[n]-Xp < 0)) or ((Xr1[n]-Xp < 0) and (Xr2[n]-Xp > 0))) and
(((Yr1[n]-Yp > 0) and (Yr2[n]-Yp < 0)) or ((Yr1[n]-Yp < 0) and (Yr2[n]-Yp > 0))));
Hope this helps...