Try blocking out both shapes before connecting them and use the existing geometry in the curve as part of the support loops around the base of the intersecting cube. That way the support loops on the intersecting shape can flow directly into the edges of the underlying curve without disrupting the segment spacing.
Here's a quick overview of what that could look like.
Below are a couple of links to other write-ups that cover relevant topology routing examples in greater detail:
Thank you so much Frank Sir ! Thanks for your overview. Subdivision is overwhelming , Thank you for sketchbook references a big help for beginners like me . Also will defenitely read forum information, Thats my fault. Thanks once again. Now lemme see what i can do.
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