I call this 'splintered payments' but it is currently not possible: https://lightningprivacy.com/en/routing-analysis
You can send multiple MPPs down the same/similar paths but you can't make them split and/or come back together at any point.
As a side note: it would be very interesting to investigate further the impact of zero base fees on this splintered payments concept. That's clearly not about privacy, but about the computational time needed to solve near-optimally the pathfinding problem by minimising the fees.
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Good one, so an HTLC cannot be "splintered" but multiple HTLCs can go through the same path independently. I wasn't aware of that lightningprivacy.com website, thanks for the reference
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