My opinion:
Ignore to.grow.invest.com as it is creating subdomains and is not a generally understood form.
Register the other two and have the single word form redirect to the dashed form using what is called a 301 Permanent Redirect.
Why?
It's easier to tell people the single word version and for them to type it in. So use that on business cards and all off-line media.
However, the dashed form works better on the Internet. The search engines can work out the words more easily and users can visualise them better. (is it ToGrowInvest or TogRowInVest?)
This is why the redirect is in place. This lest people type in the single word form, but it always ends up in the dashed form. This is the form that will propagate around the internet, accumulating ranking for your website.