[Grammar] Correct plural for a family name.

[candmsnan]

In the following two sentences which is the correct way to write the plural of Finch. This is a name, not a bird.

Have you enjoyed sitting at the Finch's? I have heard there is an ongoing investigation concerning the Finches.

 

[MikeNewYork]

In the following two sentences which is the correct way to write the plural of Finch. This is a name, not a bird.

Have you enjoyed sitting at the Finch's? I have heard there is an ongoing investigation concerning the Finches.

In your first example, you are looking for the possessive form of a plural proper name. That is Finches'. Your second is correct.