By openly homosexual, do you mean they are a homosexual couple that pretty much let us know that they are having sex?
If so, yes. If by some wonder, they were allowed to join the church, they would be held to the same Biblical standard as every other member.
Is someone is walking in disobedience, he is to be admonished, warned and appealed to in love. 2 Tim 4:2 Preach the Word; be prepared in season and out of season; correct, rebuke and encourage—with great patience and careful instruction
The admonishing or correcting is not limited to church leaders but any member in the body who is spiritually mature and led of the Spirit.
First, we are to seek private correction and/or reconciliation with the offender. The Bible says in Mat. 18:15 15"If your brother sins against you, go and show him his fault, just between the two of you. If he listens to you, you have won your brother over.
If the first step fails, witnesses are to be taken to strengthen the effect of the discipline, preferably spiritual leaders, so that if it has to be brought before the whole church it can be firmly proven and established.
16But if he will not listen, take one or two others along, so that 'every matter may be established by the testimony of two or three witnesses.' Matt. 18:16
If the second step fails, seek reconciliation and restoration through the whole body and taking it before the whole church.
17If he refuses to listen to them, tell it to the church; and if he refuses to listen even to the church, treat him as you would a pagan or a tax collector Matthew 18:17
If theydo not want to receive discipline from the church body, they are to be removed from the body.
But note this process is the same for EVERYONE, not just gay couples.