Due to bitcoin price and the hike in mining fees, I will be sending at 0.0005 btc per transaction (1 output and 1 input).
That's still incredibly low. You might be seeing up to 0.002BTC for your transaction fees for a transaction with 1 input and 1 output.
My problem is : the first transaction wont be confirmed fast, therefor all the other transactions after it wont get confirmed till the parent one is.
Is there any tip to make transaction confirmations unrelated to their parents ? like using the same change address, or sending the coins using a different approach ?
Not possible. The rules will always apply.
You're going to end up paying a lot extra in fees if you're spending inputs in the chain, doesn't make sense economically at all.