If you invite a supplier they will receive an email message with short text, a title, and a purchasing organization name.  The message refers to a page ...

You can read here at which two moments you can invite suppliers. In advance: you can invite suppliers while they are not yet able to submit an offer or...

It is not possible to be linked to a solicitation both as a buyer and as a supplier. If you invite yourself, you will not be able to accept the invitation.