Indians, particularly those from the south, use the terms “co- brother” and “co son-in-law” to refer to one’s wife’s sister’s husband.
Native speakers of English however do not use these terms. Co-brother and co-son in law are terms used in Indian English alone. If you were to introduce someone as your “co- brother” to a native speaker of English, he/she would not understand you. Within the Indian context, I guess, we can continue to use the terms.