Hello! I would say give your soulbonds a run down of the rules here on Kinmunity, and let them know proper etiquette on the site! I would say the best way to let them speak on the forum is allow them to type themselves, using your hands, and maybe allowing them to post in subjects they would fell more comfortable in, or a thread they relate more to. Soulbonds can most definitely speak on the forums on your main account, just let them introduce themselves in a post so we know who is talking! Correct anything they say if possible if it isn’t proper however... ^.=.^
As for letting them speak and type through you, just let them know that they can type, let them take over a bit, and encourage them to speak their minds, after all we do not judge here! I wish you all luck speaking together here!... ^.=.^