Code to prevent userform from saving duplicates based on 3 textboxes

I have a userform that users insert customer names and info and by clicking the save button it takes the values from textboxes and populates cells of a worksheet. The problem is the users are creating duplicate customers. What I would like to do is before saving the worksheet compare textbox 1, 2 and 3 to columns A, B and C of a worksheet before it adds the info.

I thought I could use the set range .find code with the if not range is nothing then. but that only compares the first .find.

userform.textbox1 = last name which goes into worksheet("customers").column(1)
userform.textbox2 = first name which goes into worksheet("customers").column(2)
userform.textbox3 = middle name which goes into worksheet("customers".column(3)

I figured the code below would work, but doesn't

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What if a customer has the same first and last name with a different middle intial?
I'm thinking I have to loop, but not sure how. Please help.

looping through all the rows and comparing columns A, B and C with textbox values of 1, 2 and 3 is what I had in mind.

I know how to loop through a column to find and compare 1 value with 1 cell, but multiples is what I am having a problem with.