The final phrase with them, may be interpreted as “those with whom they associate”—for example, “and all the other fellow Christians who associate with them.” The same applies to the last clause of verse 15, who are with them. The two groups of persons identified in these verses may represent persons who met in different homes for Christian fellowship and worship.

Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on Paul’s Letter to the Romans. (UBS Handbook Series). New York: UBS, 1973. For this and other handbooks for translators see here .