Settlement period

Assalem Alaycom,
If i buy an Etc/etf today 100 shares and willing to sell after 2 days but after one day i buy more from the same etc like 70 shares
Can i sell the 100 shares after 2 days as usual
How i can know which shares are sold(the settled ones or the othercos trading 212 alow to sell immediately )
After t+3 i will sell the 70 shares left ,are these 2 trades shariah compliant