user120938: Let's say I broadcast a transaction tx0 signaling RBF replaceability. Later on, send another transaction tx1 that spends the same inputs of tx0, but this time with higher fees.
In this case, tx0 is removed from mempool right? so what if then I try to send a child transaction tx0child that forms a more profitable CPFP than tx1 alone? But without the context of removed parent (tx0) this CPFP cannot work then, although it's more profitable?

user112226: Correct. tx0 is removed, and tx0child is "invalid" because it spends a UTXO that does not exist in the current chain or mempool. This could change in the future with package RBF and package relay if tx0 + tx0child are submitted as a package.
In this scenario, if the goal for tx0child was to fee-bump the original payment and RBF is possible, it probably makes more sense to just create another RBF to replace tx1.

120938: <p>Let's say I broadcast a transaction <code>tx0</code> signaling RBF replaceability. Later on, send another transaction <code>tx1</code> that spends the same inputs of <code>tx0</code>, but this time with higher fees.</p>
<p>In this case, tx0 is <strong>removed</strong> from mempool right? so what if then I try to send a child transaction <code>tx0child</code> that forms a more profitable CPFP than <code>tx1</code> alone? But without the context of <strong>removed</strong> parent (<code>tx0</code>) this CPFP cannot work then, although it's more profitable?</p>
 112226: <p>Correct. <code>tx0</code> is removed, and <code>tx0child</code> is &quot;invalid&quot; because it spends a UTXO that does not exist in the current chain or mempool. This could change in the future with package RBF and package relay if <code>tx0 + tx0child</code> are submitted as a package.</p>
<p>In this scenario, if the goal for <code>tx0child</code> was to fee-bump the original payment and RBF is possible, it probably makes more sense to just create another RBF to replace <code>tx1</code>.</p>
