If you are concern, generate script from SSMS and analyze it. Quite often SSMS will do modifications through creating a temp table instead of using ALTER TABLE. Could be a problem for big tables.

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>I need to change (increase) the size of the column in the parent table as well as a couple of child tables. E.g. part_no currently is char(20) which I need to make char(25). When I make this change to the parent table column in SSMS, I get the message prompting/asking that all child table columns will be modified too. When I say Yes, they are modified. And this is what I want.
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>But before I start making this change to the customer(s) database I have a question. Should I use a different method of increasing the size of this column? That is, is there a catch or a downside of changing the column from SSMS?
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>TIA.