neural network parameter share

the matlab neural network toolbox (CNN part) can support the layer parameters (Weights and Bias) share? I find that neither Seriesnetwork nor DAGnetwork can provide function of layer parameters sharing. Which means the created different layer occupies the corresponding storage. However,if one wants to custom a specific network (i.e.the layer1 and the layer2 may both have the same Weights). So should the training procedure don't change? while parameters updation should be referred with Add operation?