I am going to respectfully disagree with, or rather expand upon, Randy's answer. Because this is a HELOC and it's also unknown as to whether or not any money is actually being advanced for "purchase" purposes, any future advances, other than original purchase, is rescindable..therefore, to protect yourself and prevent needing RofR for every future advance, I would give RofR at closing. Any funds not attributed to purchase would need to wait 3 days.
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My opinion only. Not legal advice.
Say you'll haunt me - Stone Sour