Interesting piece on charities achieving better outcomes for their causes by working with others. I would recommend a Memorandum of Understanding to avoid gaps or duplication of effort.
there are some great examples of charities working together to campaign for a joint cause. For example, the Care and Support Alliance is a coalition of more than 70 charities that all support disabled people, older people or carers. Over the past few years the groups have had a huge impact on the Care Act and social care provision, influencing the decision making process and the content of the Act and its regulations.