OP,I am an attorney.
Please stop wasting your time here by receiving advice most of which is coming from people who have absolutely no idea about what they are talking.
Broadly speaking, I believe you need to do at least two things:
1. Visit a few law schools and sit in on some first year classes. This is arranged through the Admissions office.
2. Speak to some actually practicing lawyers. Better yet, see if you can “shadow” a few for a day at a time.
You might be interested to know that your father-in-law’s office is actually considered a small firm. There are many views of what constitutes a large law firm but in my way of thinking, 500 lawyers is the minimum. Publications like “The American Lawyer” and “The National Law Journal” annually publish different lists of law firms they say compose “BigLaw” based on things like total number of lawyers, profits per partner, etc. I know three partners at one of the top two firms. It has nearly 4,000 lawyers.
You need to have a serious sit down discussion with your father-in-law. A firm of 10-20 lawyers quite likely has a few partners. If your father-in-law were practicing on his own, he could guaranty you to take you in upon graduation (which in my humble opinion is crazy without even seeing your first semester grades) but if he has partners, he may not be able to make such a promise. How sure are you and he that three years down the road you will be hired even before you pass the bar exam?
Also, what do the lawyers in his firm do? Is it one field of law, e.g. Personal Injury, or several? What if you have no interest in what they are practicing? What if you are not good at it?
We are talking about your future. This is not the time for jokes. Don’t waste your time with the Coffee Room badchan and his fellow clowns. Find some people who will give you advice on a face to face basis. There are plenty of lawyers in our community.
Good luck!