Would it be mean to not invite DS2 to DS1's birthday party?

[Ceebee74]

Am trying to limit the numbers to DS1's 4th birthday party and he has a lot of friends!

The party is in a soft play place so I was thinking of not officially inviting DS2 (18 mo) but just paying for him to go into the soft play so he is there.

This means that I will either save myself about £6 (which doesn't actually seem like much does it?) or DS1 can invite another friend instead.

He is too young to realise what is going on although DS1 is totally devoted to him and would want him sat at the table - plus DS2 loves his food so will also want to sit at the table where the food is.

I have set the guest list at 15 - I have 14 names down so I can either add DS2 as the 15th guest or let DS1 choose someone else....don't know what to do!