I read in an article by Swami Kriyanada that once Daya Mata was continually scolded by Yogananda to make her understand not to get too much attached to him and to put divine mother first. When I sit to meditate and throughout the day I tend to think of Yogananda much more than God or divine mother. I find it easier to focus on his image than a formless one. But after reading this, I wonder if it is ok?. My second question is
After liberated souls merge into the spirit what do they do?
It is wonderful, and recommended, for you to focus on Yogananda in meditation. Tuning in to Yogananda’s image or vibration helps you attune to God.
The difference in the case of Daya Mata is that, since she knew Yogananda personally, it was easy to become attached to his delightful human personality, to their personal relationship which seemed to be like father and daughter, and to forget that Yogananda was like glass, allowing God’s light to flow perfectly through him. Whatever sense she might have had — as would be natural when you know someone personally — that they had a personal relationship, was a delusion.
Those of us who haven’t known Yogananda in the flesh are not in danger of becoming attached to him in a personal way, so Nayaswami Kriyananda has explained.
About your second question: after souls merge into spirit, what do they do. Your question comes from our human attachment to action and doing. God IS. When we become God we ARE. Beyond that, I really can’t say! That state is beyond our imagining. It would be helpful to put aside philosophical questions like that, and try to meditate on the idea of inner stillness, which will take you to that exalted state.
Blessings on your meditations,