Can you do a waiver signature in the online wizard?
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Yes and No.
When your customer books online they are presented with your terms and conditions and have to check a box saying that they have read them:
(so in a sense you can get them to agree to waiver information before arrival - but you will have to get this checked with legal team where you are.)
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However this is not really a signature, as we don't know if they are booking on a device (touch screen) that can take a signature.
See also
So how about if you want an online booking - and then to capture signature on customer arrival?