Re: have somebody with us
If this is only the invitation and you don't yet know if they will definitely be coming to dinner, I wouldn't say that at all. I would say "We look forward to hearing from you" (formal), or "Let us know if you can come asap!"
Once they have accepted the invitation and you know they are coming, I would use "We're looking forward to seeing you", "We're looking forward to you coming over", "We're looking forward to dinner with you".
Remember - correct capitalisation, punctuation and spacing make posts much easier to read.