Ok so this may be a stupid question but I can't find any info online. I am hunting for a boat in Missouri they require all 3 titles to reg. I went and looked at a boat today and the lady wanted to write the total price on all 3 titles. In Missouri they tax you on every title. Should she not divided the price between the 3 titles so I don't pay tax on all 3 at the price I paid for all? I was going to give her $8500 for boat/motor and trailer and she wants to write $8500 on each title. I told her to stop I would need more info. She would not divide it between the 3 for me.

You are correct.  Select a price for each and have it written on the title for that item.

Same thing here in Ohio. I split the price when I sold my last boat in 3rds.

Advise her that if she writes 8500 on all three it goes on county/state record as selling each item for 8500, thus the state will think she took in $25,500 income and she could get audited! Yes you would have to pay whatever sales tax is for $25,500 to transfer the title if she does it that way.