# FAQ and Troubleshooting

## Can I apply multiple instances to a single Thing?

No, a thing can only be associated with a single instance at a time. If your instance is missing properties, you can add them to the dimension/instance at any time.

## I made some edits to a dimension, but my datasets haven't changed at all?

Any changes you make to dimensions, instances, or things will not be applied to your datasets until machine master data has been republished. This can be done using the button in the top-right-hand corner of the machine master data list.

## I am using a thing's **instance** in one of my datasets. What will happen to this dataset if the instance is deleted, or removed from the thing?

Your dataset will continue to work, **provided** your dataset still contains instances of the same dimension type as the instance that was removed. The thing which has no longer an associated instance will just have NULL values in the relevant columns. 

For example let's say you have two instances A and B, which are both of the same dimension types. These are both applied to things and used in the same dataset. If A is then removed from its thing the dataset will continue to work, with NULL values shown in cells that previously contained A's data. However, if B is then also removed from its thing, the dataset will no longer be able to execute.

## What happens when a dimension is deleted?

The dimension itself will be deleted, along with any instances using this dimension. Any attribute of this dimension type (sub-dimension) will also be removed from their parent dimension/instance. Any datasets using attributes of this dimension will no longer execute and will need to have the relevant columns removed. 

## Can I have an instance with no values?

Yes, if it does not contain any [subdimensions](/manual/sf-platform/machine-master-data/dimensions.md#subdimensions). All attributes except subdimensions are allowed to be empty.


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