Autoencoder with variable size of inputs

Hi, I try to embed nodes of a graph, by using an Autoencoder with linear layers. But the graph is dynamic so number of its nodes may be changed at each time step.
How can I add some additional nodes and corresponded weights to the “input layer” of AE (at time t), to use it for next time step (t+1)? I don’t want to change the hidden layers and other weights ,…