Yes, you can. However, you must adhere to the requirements to access Custom Portfolios:
You must keep $10,000 or more invested in an InvestSMART Portfolio, excluding Fundlater.
You must invest $2,000 or more in your preferred Exchange Traded Fund
You cannot hold more than five preferred Exchange Traded Funds
You can reallocate existing holdings in your online account using the Modify Allocations tool.