This is right, but OP shouldn't do that.

The coin OP received in the unconfirmed transaction is too low and it's not enough for covering the fee. Therefore, the fee required to be paid for the child transaction will be bigger than the value of that coin and OP would waste money on transaction fee.

Also, with adding another coin to be used as input of the transaction, OP would increase the transaction size and transaction fee.
Of course, this would act as consolidation of outputs, but it's not a good time for that as the network is so congested.