Has any one noticed the importance of 3rd house in Navamsha D9 ? even if you have Strong Ve , Strong 9th Cusp but trashed 3rd Cusp and 3rd Lord ? any practical experience to share ?
I have not checked this but I think person with a destroyed 3rd cusp in d9 won't find any meaning and purpose for the work done along with siblings or his co workers at which point I want to see how they doing in d3. If that's crashed too, means they are not able to get along with siblings, neighbors, Co workers etc.
And if the planets damaging the 3rd cusp are in bad DA/LA rasi aspecting key 9th factors in D9, then they should have negative effects on marriage too..
One thing that comes up is the axis of 9/3 and the opposing and complementary aspects of this pair. If 9th is harmony in marriage than 3rd would implicate competition, a source that could disturb the harmony of the 9th. Also 3rd is desires and concepts that can cause interference with inspiration and dharma of the 9th. In practice I have not noticed 3rd house coming up in Navamsa charts and relationship reading in a big way, but would be interested in hearing about what you're are seeing.
I have someone's chart that comes to mind with Sa, Ra and Ma rasi aspecting the 3rd bhava in D1 but Ld of 3rd in D3 is EX and in D9 it's better than worse. So there is a very wide ranging mix here and the person exhibits this. Sometimes seemingly no social skills with a lot of antagonism and other times very diplomatic and can get along with almost anyone. When they are not in the grip of the harmful LA the more diplomatic and agreeable side is able to manifest.