SSAS - Is it possible to add an attribute to an existing dimension w/o redeploying the entire cube

I have a dimension Entity with just Key and Value attributes. We need to add a new attribute, IsSpecial with a default member of [False].

When I try to run the xmla, I get the following error:

Errors in the metadata manager. The cube with the ID of 'X', Name of 'Y' was invalidated by operations in the transaction.

Here's a fragment of the XMLA used to alter the dimension

<Dimension>
    <ID>Dim Entity</ID>
    <Name>Entity</Name>
    <UnknownMemberName>Unknown</UnknownMemberName>
    <Attributes>
        <Attribute>
            <ID>Dim Entity</ID>
            <Name>Entity</Name>
            <Usage>Key</Usage>
            <EstimatedCount>119</EstimatedCount>
            <KeyColumns>
                <KeyColumn>
                    <DataType>Integer</DataType>
                    <Source xsi:type="ColumnBinding">
                        <TableID>shared_DimEntity</TableID>
                        <ColumnID>EntityKey</ColumnID>
                    </Source>
                </KeyColumn>
            </KeyColumns>
            <NameColumn>
                <DataType>WChar</DataType>
                <DataSize>32</DataSize>
                <Source xsi:type="ColumnBinding">
                    <TableID>shared_DimEntity</TableID>
                    <ColumnID>EntityValue</ColumnID>
                </Source>
            </NameColumn>
            <AttributeRelationships>
                <AttributeRelationship>
                    <AttributeID>IsSpecial</AttributeID>
                    <Name>IsSpecial</Name>
                </AttributeRelationship>
            </AttributeRelationships>
        </Attribute>
        <Attribute>
            <ID>IsSpecial</ID>
            <Name>IsSpecial</Name>
            <KeyColumns>
                <KeyColumn>
                    <DataType>Boolean</DataType>
                    <Source xsi:type="ColumnBinding">
                        <TableID>shared_DimEntity</TableID>
                        <ColumnID>IsShadowTracking</ColumnID>
                    </Source>
                </KeyColumn>
            </KeyColumns>
            <NameColumn>
                <DataType>WChar</DataType>
                <Source xsi:type="ColumnBinding">
                    <TableID>shared_DimEntity</TableID>
                    <ColumnID>IsShadowTracking</ColumnID>
                </Source>
            </NameColumn>
            <DefaultMember>[Entity].[IsSpecial].[False]</DefaultMember>
        </Attribute>
    </Attributes>
    <Hierarchies>
        <Hierarchy>
            <ID>Hierarchy</ID>
            <Name>Hierarchy</Name>
            <Levels>
                <Level>
                    <ID>IsSpecial</ID>
                    <Name>IsSpecial</Name>
                    <SourceAttributeID>IsSpecial</SourceAttributeID>
                </Level>
            </Levels>
        </Hierarchy>
    </Hierarchies>
</Dimension>

Any suggestions?

I doubt there is a way of doing this.
When changing dimension model you also modify cubes which use that dimension. Without redeploying the whole cube, metadata manager doesn't know about changes in cube.

The same situation occurs when changing dimensions in BIDS on-line - appropriate cubes are affected so they need to be deployed again.

"Recall that ROLAP partition-mode storage means that source data is not copied to the SSAS destination. Another characteristic of ROLAP partition storage is that aggregations are written back to relational tables in the source schema."

"To set a dimension as a ROLAP dimension, open the Dimension editor in BIDS, and in the Properties window for that dimension change the StorageMode property from the default MOLAP to ROLAP"

"though this requires Enterprise Ed of SSAS"