All donations taken through the Fundraising page must go to the organisation on the TryBooking account, that also matches the ABN entered. It is up to that organisation as to how those donations are then distributed, allowing you to disburse them onto either an individual or charity of your choice.
To accept donations on behalf of a 3rd party, you must have authority from that organisation. To ensure that you comply, it is recommended that you avoid using the phrases such as "on behalf of 3rd Party Name" or include the name of the 3rd Party in the name the Fundraising page. Instead, you will need to be general as to the cause you are raising funds for, and in the page description simply express that the funds will be directed to the 3rd Party.
Use of the 3rd party's Intellectual property on your Fundraising page without permission is also not allowed. This includes uploading images with their logo and linking to their social pages.