TCP/IP Urgent Help

Dear All,

I have here my network consist of 2 seperate locations at all , the first
one is our head office and it has 50 users in side it .

the second locations is farway from us and there is no any connection at all
between them, they are about 60 users .

each locations is working with this subnet mask 255.255.255.0 and the
IP-Address is 192.168.1.X .

all the 2 locations are under workgroup name it with ( GROUP1).
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Now the situation is changed littile bit , we will have wireless and we will
coneect to them in the same subnet .

My question is , i do not know should i make each company to be separeat
subnet and connect between them using router , or there is no any Problems by
leaving it like that , all of them is under one subnet ?

But if i left them under one subnet , what about the broadcast, i will have
delay is that correct ?

2- why iam making 2 subnets, and connect between them by router , as long as
before router they will be able to see each other , and after router they
will be able to see each other as well , so why i am using 2 subnet , is that
because of Broadcast, if so, and if i made each company to work with its
subnet, do you think i will have seperate broadcast domain ?

Can any one please update and help me , as long as i am still new to it ?

Thanks .