Yes! There are no limits to the number of RESPs you can open.
However, there’s a limit to how much may be contributed for each future scholar. So if you’ve opened an RESP for a grandchild, and another loved one in that child’s life also has an RESP for that same child, you’ll have to make sure you keep the lines of communication open to ensure that the total amount contributed in the child’s name doesn’t surpass $50,000.