Hi Ram,
your RAD application is behaving as an independent object, i am not sure why the lock object is not helpful for you here. I do not have sap system access now.
I can give one custom alternate if you wish try and implement it.
Instead of deleting the entity upon delete event using lr_entity->delete, store the entry in one custom internal table and then delete the database table entries using custom table in save event method. you need to take care of clearing the buffer internal table.
Regards,
Dharmakasi.