You can look at the Upgrade Guide which comes with BSM9. you will have to go through BAC8.07. one important note to mention: there were many changes between BAC7 and BAC8, and even more changes in BSM9. even though you can upgrade and keep all your configuration and data, I am not sure that this is the pass you want to take. HP PS will be able to assist you and recommend the right direction.
Thanks Parag and Asaf for your reply but I need a document using which I can convince my client for upgrade with valid data. Can anyone provide me any document which will list out all upgrade steps in live environment.
Also I am aware that 7.x is now out of support hence upgrading BAC 7.x is now a must task to complete on priority.
Upgrade steps for such complex upgrade (BAC 7.55 to BSM 9.2x) will heavily depend on the customer environment and customer specifics. So don't think that anybody can have such document ready for you.
I would first try to convince the customer not to do the upgade, but instead build out the new BSM 9.2x from scratch and manually recreate all necessary configurations. That would be much faster. Especially taking into account drastic differences between 7.x and 9.x versions of the product.
But if your customer does insist on the actual upgrade, you'd better contact HP Professional Services as you were already told. Unless you consider yourself as a very knowledgable and experienced with BSM, and did BAC/BSM upgrades in the past.