Maybe the last part was just a joke

I'd like to point out that no, vasectomies are NOT reversible. Sometimes it is possible, but they are not considered to be reversible in general, so you really shouldn't rely on that being the case.

Even if it IS reversible, by the time you pay for both procedures, most of the money would be gone anyway. You weren't expecting anything, so just chalk it up to him being an asshat and move on with your life.

A portion? If you live in the United States of America you will have to use nearly all of it. Then you will have gotten a vasectomy to inherit about $127 dollars

Your grandfather was an asshole and it was not your fault that you were born out of wedlock.

Don't accept the money. $3500 will mean nothing when you decide to have children. The asshole's dead and he can't put you down anymore. Let the other family members fight over the money. You're worth more than a couple thousand bucks.

Don't do it,

They won't perform the surgery unless you have at least one existing child. It also doesn't specify when you have to have it, I'm sure. It's also safer than a C-section, so stop complaining. It's also not castration, so you're fully functional. After a kid (or two if you're a masochist), totally worth it! Especially because kids don't come cheap and ruin everything. You won't want an accidental third child. The 3.5k is just a plus.

So don't take it.

Pay a shady doctor to make up some records claiming you got it, then if you later have children claim it was botched but are deciding not to sue since you shouldn't of gone to the cheapest one.