The only thing I would concern myself with (if only I could have more than 2 yorkies...
) would be affording emergency care. Would you be able to afford vet bills if all 4 of them contracted parvo? Or were all hurt in some way? I hate to think about these instances, but I think it is important to be able to afford emergency care for all of our pets. If this isn't an issue, then by all means, go for it! I bet the power of the pack you already have will help a newbie fit in just fine! LUCKY YOU! (and post pics if you get another, please!
)