GRIDGEN REDIMENSION

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I need to redimension the grids on a connector, without changing the starting and ending distance of the first and the last grid point respectively. Here is an example, Connector with first grid point say 0.1 mm and the remaining grids are equidistant say 0.3 mm apart and the ending distance say 0.2 mm. Now I wish to get the equal gridpoints 0.9 mm apart i.e every fourth grid point remains, but I want to keep the same constraints at the beginning and end. How can I do this? Thanks