The Sri Sathya Sai Ashram celebrates Christmas every year in a grand manner. The previous evening usually comprises a program by an International Music Orchestra, that plays Christmas Carols. On Christmas Morning, (proper) Christians and other Hindu devotees from all over the world and India, go in a candle procession around the Ashram. Christmas evening sometimes has a play or cultural program on the life and message of Jesus Christ, or a music program by an international artist.
The Ashram is decorated colorfully with stars, lights etc. In the last few years, every year, a different country is given charge of the grand decoration activity. Devotees from that country decorate the ashram with volunteers.
When Sri Sathya Sai Baba was alive, he gave a discourse on Christmas every year, mentioning the good qualities to be learnt from Christ's life and his relationship with God. The celebrations every year, make hardly any distinction between Hindus residing Abroad/India and overseas citizens/born christians, in terms of participation. The activities often begin with a chant of Omkar and end with a chant of Samastha Loka Sukino Bhavanthu and Om Shanthi as on the other Hindu festival days.
http://www.srisathyasai.org.in/pages/ashraminfo/Christmas.htm
http://media.radiosai.org/journals/vol_13/01DEC15/Christmas-Celebrations-at-Prasanthi-Nilayam-2015.htm