@AleemAlam I don't know if you are still facing this problem. I solved it using HTML5 message API. But you need to be in control of both the parent window and the iframe window as we need code changes on both sides.

I also have the same problem, injectedWeb3 for polkadot.js extension was not passed to the iframe
while it have the wallets like talisman

@ankitShogun how did you do this? do you pass the injectedWeb3 value from the parent side using postMessage?

@teodorus-nathaniel What i did was to create a sort of communication layer between iframe and the extension using the parent. Event based communication in short.
In general you need the extension for signing the transactions so whenever it was needed inside the dapp (iframe), it will post a request message to parent with the required data.
Parent will take that data, sign that using polkadot extension and then fire back an event targeting the iframe with the signed data.
Not sure if passing the injectedWeb3 will work as you need the UI feedback of polkadot extension while signing the message.

@ankitShogun is there any example code on how to communicate between iframe and parent?

@jacogr i'd love to help contribute to this feature if it could be added.