The problem is more architectural than anything. Both a 'Sketch' and a 'Bridge Curve' are 'features'. And a 'feature' is an object which contains the data (recipe), both geometric objects, as well as the numerical parameters and/or the rules that define how these objects are related to each other and how they are to update when one or more of the objects or parameters are changed. But the issue is that each 'feature' must contain ONLY a single recipe, even though it might be very complex, it only defines the behavior of a SINGLE 'feature'. As a consequence of this, a 'feature' cannot be part of another 'feature'. Also, 'features' update in timestamp order (this will be important in a minute) but inside a 'Sketch' the relationships are solved simultaneously, or all at once.
To see what I mean, let's take your 'Bridge Curve' inside a 'Sketch' scenario. Now we might be able to handle this, after a lot of really creative coding, if there was ONLY one 'Bridge Curve' in the 'Sketch', but if that was possible, people would immediately demand for support for more than one and here's where that fails. Let's say you were able to create a true 'Bridge Curve' feature in a 'Sketch' and you decided that you really needed TWO 'Bridge Curves' and even if the geometry that they were related to was not directly shared, since all of that geometry was part of the 'Sketch' when the sketch updates all the relationships, as previously mentioned, need to be solved in one turn of the crank, as it were, but how can that happen when the 'Bridge Curves', which must be solved in timestamp order, are going to also contain relationships (constraints) relative to other 'Sketch' objects and if one of those other objects is a second 'Bridge Curve', how can a solution be found? It just doesn't work that way.
The important thing to remember is that each 'feature' must contain ONLY the data (recipe) that is part of that 'feature', period. Yes, it may be related to another 'feature' and even depend on it when it updates, but that's fine, because they will be updating one at a time, in timestamp order. That can't happen if 'features' were allowed to be created inside another 'feature'.
Anyway, I hope I made it clear as to why this is NOT possible.
John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
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