Since E-on makes many  "editions" available of the same program "version', a "Sidegrade" (their word) AFAIK is merely trading up to a higher edition within the same version.

In your case, I don't think you would be eligible to receive a "free upgrade" unless you did one of the following...(Before the promotion expires)

• Upgrade to Vue XStream since you've got V5I already.
• Wait for the "special pricing" deals for Pre-orders / Late Buyers.
• Purchase another Vue 5 licence.