On the multiplicities of families of complex hypersurface-germs
  We show that the possible drop in multiplicity in an analytic family $F(z,t)$ of complex analytic hypersurface singularities with constant Milnor number is controlled by the powers of $t$. We prove equimultiplicity of $\mu$-constant families of the form $f + tg + t^2h$ if the singular set of the tangent cone of $\{f = 0}$ is not contained in the tangent cone of $\{h = 0}$. 
Camille Plenat and David Trotman
math.AG math.CV