Will the deceased be punished in their grave if they bought a television for their children without prior knowledge that they already had a satellite dish?

We have previously explained the ruling on owning and watching television, and you can refer to Fatwa No. 1886. This will help determine the permissibility of your brothers owning a television based on their adherence to the Shariah guidelines in its use. As for your question about whether your father will be punished because of it, this is among the matters of the unseen, which cannot be definitively asserted. However, if the father knows that his sons will not adhere to the Shariah guidelines in using the television, and he buys it for them, then he is considered a partner with them in sin and is exposed to Allah's punishment. Therefore, you should advise your brothers to get rid of the device if they do not adhere to the Shariah guidelines in its use.