Definatly call! If you do two parties of 5 then you run the chance of them getting canceled for double booking, unless you put them under 2 name and numbers. Or you have the chance of not being near each other since they are not linked. I tried making ADRs for 8 online since at the time thats what we had in our party but had no luck figured nothing available. 2 more people decided to join us so I called and was able to get what we wanted for 10. Heck I was even able to get some things for our party of 5 on the phone that I couldn't online.