All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad (ﷺ) is His Slave and Messenger.
If what is meant is that you are acting as an agent on behalf of someone else in the contract, then you are not required to disclose that to the one you are purchasing from. Rather, an agent may attribute the contract to himself.
It is mentioned in Durar al-Hukkam, a commentary on Majallat al-Ahkam, Article (1461): It is not a condition to attribute the contract to the principal (the one on whose behalf the agent is acting) in sales, purchases, or leasing. If he does not attribute it to his principal and instead suffices with attributing it to himself, it is also valid. [End quote].
However, if your intention is something else, then please clarify it so that we may answer accordingly.
Allah Knows best.