Hi @DavidTunnard. So, do you just want to know how to select multiple things at the same time manually, or are you looking for an iLogic rule that you can run that will select multiple assembly components for you? Manually, you can hold down the Control keyboard key while you select multiple things. By code, once you have obtained a reference to the Document object you are working with, you can use the Document.SelectSet property to access its SelectSet object. Once you have that, you can either use its Select method, or its SelectMultiple method. The SelectSet object is where the things you manually select are stored temporarily. There is also a method for creating a HighlightSet, but that does not sound like what you really want here, because those are not necessarily also in the SelectSet, unless you plan it that way. The color of stuff we normally select is dictated by application level settings, but we can control the color of a HighLightSet by code. How you want to select those parts is another aspect that we do not know yet. If you want to be able to manually select them with your mouse, while the rule is running, you can use the Pick method, then add each object you pick to a collection, then when done selecting, add the collection to the SelectSet. If you want to select them some other way, using some more automation, then we would need to know what is unique about those components, so that we can find them by code.
Wesley Crihfield

(Not an Autodesk Employee)