Not naturally, but if you create a list argument and pass in a blockobject as the first element you can then get it in the function. That’s the theory at least, but I can’t get that to work, so I’ll say no. Maybe someonce can create a sample that works? @Vegz78 @Blobbey 
You can totally modify block objects on runtime, even if they’re in an array! Here I put together a little example of changing a number value in a nested block object, as well as retrieving it.
In the start block, I just defined a nested array of empty objects. Basically, using the modifyNumber method I can pass in a row, column (x and y) and a numerical value. There, I get the object and set its value using the ususal set number block from the block objects.
You don’t have to do any additional work, the object is automatically updated because we referenced it directly in the array, and not a copy of it.
Then, we just get that value in the getNumber function. As you can see in the start block below the definition, I set the value at [1, 1] to 20, and then retrieve it with the getNumber function. The value we’ll get is 20 because we set it above. You can check this code out yourself here