Adding features to the already selected feature layer

Hi All,

How can i add features to the already selected layer.

1.original layer having thousands of recored
2.i selected some features in my requirement and created as a separate layer
3. now i need to add some another features related to the same. so what i can do for this case
in general case what i'm doing is copying features from selected layer and copying new features from original layer and do the selection query with the object-id.

please help me with the easy process to do this because i need to this often times...

Thanks
Ganesh