Unknown leak in 99 subaru legacy

My Grandmother has a '99 Subaru Legacy, it has about 67,000 miles and has one serious problem–there is water in the front passenger and driver sides of the car after it rains. I have taken a look at the car myself and all the molding seems to be intact, the windows shut firmly, and for the life of me I cannot figure out how water keeps getting in, and still after it rains there are puddles under each seat making the car smell like a wet dog all the time. Please can you help me figure out what the problem is and possibly how to fix it, thank you.

If the car has a sunroof/moonroof, that would be my prime suspect. Over time, the drains can become clogged and when it rains, what should go down those drains winds up in the passenger compartment.

The plastic trim at the bottom of the windshield is overtop a bit of a “trench” that is supposed to drain out the bottom of the car. There are little drain holes probably both in the trim and down underneath.

The entire area often gets completely clogged up with leaves & twigs & other such gunk. You can then get water coming in that way. Clean out that whole area including the drains.

It is also the case that there are some body leaks that are just very hard to find. If you clean out under the windshield and it continues to leak it might be easiest to stop at a body shop.