With God there is an endless supply of love and concern for His creation. Since godliness amounts to mimicking God, we too are to find an endless supply of love for His creation. Increasing our love for a growing brotherhood should not diminish the love we feel for the brothers we have always associated with.
Our supply of love and concern for our fellow travelers should never run out. In fact, our love for them should be Rock solid evidence of our regeneration. The apostle John, who loved writing about love, says as much in 1 John 3:14 when he writes "We know that we have passed from death to life, because we love our brothers."
In 1 John 3:11 he writes "This is the message you heard from the beginning: We should love one another." He makes numerous references to the commands of Jesus "that you heard from the beginning" throughout his writings, and they all point back to Jesus' command to love one another. I'm confident that "one another" means all brethren redeemed by Christ, not just one or two little sects of them.
The love of God is not a zero-sum game. There's more than enough love available to go around with extra to spare. The nice thing is that if we ever seem to come up short, we can always go back to the Well and draw some more.