If you are campaigning with other charities, you should make sure that the joint activities are consistent with each charity’s purposes.
If you are campaigning with non-charities, you must make sure that they do not compromise your charity’s independence by being associated with any political parties, politicians or candidates standing in an election. You should think carefully before campaigning with non-charities about how this might look to the public and how you can justify the campaigning activity as advancing your charity’s purposes.
There are specific rules about joint campaigning under electoral law that will apply to charities in some in some circumstances. If you are considering campaigning jointly with others you should consult the Electoral Commission guidance on this matter. You can read more about how electoral law affects political campaigning by charities here.