Yes! You can have all of our investment products open at the same time. Only one can be the automatic destination for new money you put into the platform though, so bear that in mind when adding funds.
You can also mix and match how you want your repayments to be reinvested. For example, you can invest new money into Core, and have your repayments go into Plus. Just remember that the £1,000 minimum investment still applies: so your money won't be lent out until you reach this amount (through your repayments or by topping up your account).
Once you've opened an IFISA acount, you can opt to invest in both options if you like – just be sure to not exceed your annual allowance (across our IFISA and any others you may have).
You can change your settings any time via the Manage tab on your investment summary.